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Chen L, Zhao W, Xing K, You M, Wang X, Zheng RK. Anomalous Hall effect in Nd-doped Bi 1.1Sb 0.9STe 2 topological insulator single crystals. Phys Chem Chem Phys 2024; 26:2638-2645. [PMID: 38174415 DOI: 10.1039/d3cp05850f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Topological insulators are emerging materials with insulating bulk and symmetry protected nontrivial surface states. One of the most fascinating transport behaviors in a topological insulator is the quantum anomalous Hall effect, which has been observed in magnetic-topological-insulator-based devices. In this work, we report successful doping of rare-earth element Nd into Bi1.1Sb0.9STe2 bulk-insulating topological insulator single crystals, in which the Nd moments are ferromagnetically ordered at ∼100 K. Benefiting from the in-bulk-gap Fermi level, electronic transport behaviors dominated by the topological surface states are observed in the ferromagnetic region. At low temperatures, strong Shubnikov-de Haas oscillations with a nontrivial Berry phase are observed. The topological insulator with long range magnetic ordering in Nd-doped Bi1.1Sb0.9STe2 single crystals provides a good platform for quantum transport studies and spintronic applications.
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Affiliation(s)
- Lei Chen
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
| | - Weiyao Zhao
- Department of Materials Science & Engineering, and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, VIC 3800, Australia
| | - Kaijian Xing
- School of Physics & Astronomy, Monash University, Clayton, VIC 3800, Australia
| | - Mengyun You
- Institute for Superconducting and Electronic Materials, and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Innovation Campus, University of Wollongong, NSW 2500, Australia
| | - Xiaolin Wang
- Institute for Superconducting and Electronic Materials, and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Innovation Campus, University of Wollongong, NSW 2500, Australia
| | - Ren-Kui Zheng
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
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2
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Khan NZ, Khan SA, Chen W, Padhiar MA, Abbas MT, Ullah Z, Runowski M, Xu X, Zheng RK. The developments of cyan emitting phosphors to fulfill the cyan emission gap of white-LEDs. Front Chem 2023; 11:1274410. [PMID: 37915542 PMCID: PMC10616965 DOI: 10.3389/fchem.2023.1274410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 09/07/2023] [Indexed: 11/03/2023] Open
Abstract
Future generations of solid-state lighting (SSL) will prioritize the development of innovative luminescent materials with superior characteristics. The phosphors converted into white light-emitting diodes (white LEDs) often have a blue-green cavity. Cyan-emitting phosphor fills the spectral gap and produces "full-visible-spectrum lighting." Full-visible spectrum lighting is beneficial for several purposes, such as light therapy, plant growth, and promoting an active and healthy lifestyle. The design of cyan garnet-type phosphors, like Ca2LuHf2Al3O12 (CLHAO), has recently been the subject of interest. This review study reports a useful cyan-emitting phosphor based on CLHAO composition with a garnet structure to have a cyan-to-green emitting color with good energy transfer. It could be employed as cyan filler in warm-white LED manufacturing. Due to its stability, ability to dope with various ions suitable for their desired qualities, and ease of synthesis, this garnet-like compound is a great host material for rare-earth ions. The development of CLHAO cyan-emitting phosphors has exceptionally high luminescence, resulting in high CRI and warm-white LEDs, making them a viable desire for LED manufacturing. The development of CLHAO cyan-emitting phosphors with diverse synthesis techniques, along with their properties and applications in white LEDs, are extensively covered in this review paper.
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Affiliation(s)
- Noor Zamin Khan
- School of Physics and Material Sciences, Guangzhou University, Guangzhou, China
| | - Sayed Ali Khan
- Hoffmann Institute of Advanced Materials, Shenzhen Polytechnic, Shenzhen, China
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, United States
| | - Weilong Chen
- School of Physics and Material Sciences, Guangzhou University, Guangzhou, China
| | | | - Muhammad Tahir Abbas
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, China
| | - Zakir Ullah
- Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization, North China Electric Power University, Beijing, China
| | - Marcin Runowski
- Departamento de Física, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
- Faculty of Chemistry, Adam Mickiewicz University, Poznań, Poland
| | - Xin Xu
- CAS Key Laboratory of Materials for Energy Conversion, School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, China
| | - Ren-Kui Zheng
- School of Physics and Material Sciences, Guangzhou University, Guangzhou, China
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Wang ZC, Zhang Y, Li ZN, Li SS, Ying JS, Yan W, Chen L, Zhang SJ, Luo FS, Zhao W, Ye M, Zheng RK. High-mobility spin-polarized two-dimensional electron gas at the interface of EuTiO 3/SrTiO 3heterostructures. J Phys Condens Matter 2023; 36. [PMID: 37738991 DOI: 10.1088/1361-648x/acfc90] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 09/22/2023] [Indexed: 09/24/2023]
Abstract
Spin polarization of two-dimensional electron gas (2DEG) at the interface of EuTiO3/SrTiO3(STO) heterostructures has been theoretical predicted and experimentally observed via x-ray magnetic circular dichroism and polarized x-ray absorption spectroscopy, which, however, is lack of magnetotransport evidence. Here, we report the fabrication of high-quality EuTiO3/STO heterostructures by depositing antiferromagnetic insulating EuTiO3thin films onto STO substrates. Shubnikov-de Haas oscillation, Hall, and magnetoresistance (MR) measurements show that the interface is not only highly conducting, with electron mobility up to5.5×103cm2V-1s-1at 1.8 K, but also shows low-field hysteretic MR effects. MR of ∼9% is observed at 1.8 K and 20 Oe, which is one order of magnitude higher than those observed in other spin-polarized 2DEG oxide systems. Moreover, the heterostructures show ferromagnetic hysteresis loops. These results demonstrate that the high-mobility 2DEG is spin polarized, whose origin is attributed to the interfacial Ti3+-3dstates due to oxygen deficiency and the exchange interactions between interfacial Eu spins and itinerant Ti-3delectrons.
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Affiliation(s)
- Zhao-Cai Wang
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China
| | - Ying Zhang
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China
| | - Zheng-Nan Li
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China
| | - Shuang-Shuang Li
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China
| | - Jing-Shi Ying
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China
| | - Wei Yan
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China
| | - Lei Chen
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, People's Republic of China
| | - Shu-Juan Zhang
- School of Materials and Mechanic & Electrical Engineering, Jiangxi Science and Technology Normal University, Nanchang 330038, People's Republic of China
| | - Fu-Sheng Luo
- School of Physics and Electronic Information, Gannan Normal University, Ganzhou 341000, People's Republic of China
| | - Weiyao Zhao
- Department of Materials Science & Engineering, Monash University, Clayton VIC 3800, Australia
| | - Mao Ye
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, People's Republic of China
| | - Ren-Kui Zheng
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, People's Republic of China
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Zhang SJ, Chen L, Li SS, Zhang Y, Yan JM, Tang F, Fang Y, Fei LF, Zhao W, Karel J, Chai Y, Zheng RK. Coexistence of logarithmic and SdH quantum oscillations in ferromagnetic Cr-doped tellurium single crystals. J Phys Condens Matter 2023; 35:245701. [PMID: 36940480 DOI: 10.1088/1361-648x/acc5ca] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 03/20/2023] [Indexed: 06/18/2023]
Abstract
We report the synthesis of transition-metal-doped ferromagnetic elemental single-crystal semiconductors with quantum oscillations using the physical vapor transport method. The 7.7 atom% Cr-doped Te crystals (Cr:Te) show ferromagnetism, butterfly-like negative magnetoresistance in the low temperature (<3.8 K) and low field (<0.15 T) region, and high Hall mobility, e.g. 1320 cm2V-1s-1at 30 K and 350 cm2V-1s-1at 300 K, implying that Cr:Te crystals are ferromagnetic elemental semiconductors. WhenB// [001] // I, the maximum negative MR is ∼-27% atT= 20 K andB= 8 T. In the low temperature semiconducting region, Cr:Te crystals show strong discrete scale invariance dominated logarithmic quantum oscillations when the direction of the magnetic fieldBis parallel to the [100] crystallographic direction (B// [100]) and show Landau quantization dominated Shubnikov-de Haas oscillations forB// [210] direction, which suggests the broken rotation symmetry of the Fermi pockets in the Cr:Te crystals. The findings of coexistence of multiple quantum oscillations and ferromagnetism in such an elemental quantum material may inspire more study of narrow bandgap semiconductors with ferromagnetism and quantum phenomena.
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Affiliation(s)
- Shu-Juan Zhang
- School of Materials and Mechanic & Electrical Engineering, Jiangxi Science and Technology Normal University, Nanchang 330038, People's Republic of China
| | - Lei Chen
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, People's Republic of China
| | - Shuang-Shuang Li
- School of Materials Science and Engineering and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China
| | - Ying Zhang
- School of Materials Science and Engineering and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China
| | - Jian-Min Yan
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong 999077, People's Republic of China
| | - Fang Tang
- Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500, People's Republic of China
| | - Yong Fang
- Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500, People's Republic of China
| | - Lin-Feng Fei
- School of Materials Science and Engineering and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China
| | - Weiyao Zhao
- Department of Materials Science & Engineering, & ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, VIC 3800, Australia
| | - Julie Karel
- Department of Materials Science & Engineering, & ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, VIC 3800, Australia
| | - Yang Chai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong 999077, People's Republic of China
| | - Ren-Kui Zheng
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, People's Republic of China
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Chen TW, Li SS, Tang F, Ying JS, Zhang Y, Wang ZC, Zhang SJ, Luo FS, Chen L, Fang Y, Zheng RK. Correction: Magnetotransport and magnetic properties of Cr-modified Mn 2Sb epitaxial thin films. Phys Chem Chem Phys 2023; 25:7550. [PMID: 36848140 DOI: 10.1039/d3cp90067c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Correction for 'Magnetotransport and magnetic properties of Cr-modified Mn2Sb epitaxial thin films' by Ting-Wei Chen et al., Phys. Chem. Chem. Phys., 2023, 25, 5785-5794, https://doi.org/10.1039/D2CP05442F.
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Affiliation(s)
- Ting-Wei Chen
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Shuang-Shuang Li
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Fang Tang
- Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500, China
| | - Jing-Shi Ying
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Ying Zhang
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Zhao-Cai Wang
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Shu-Juan Zhang
- School of Materials and Mechanic & Electrical Engineering, Jiangxi Science and Technology Normal University, Nanchang 330038, China
| | - Fu-Sheng Luo
- School of Physics and Electronic Information, Gannan Normal University, China
| | - Lei Chen
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
| | - Yong Fang
- Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500, China
| | - Ren-Kui Zheng
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China.,School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
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6
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Chen TW, Li SS, Tang F, Ying JS, Zhang Y, Wang ZC, Zhang SJ, Luo FS, Chen L, Fang Y, Zheng RK. Magnetotransport and magnetic properties of Cr-modified Mn 2Sb epitaxial thin films. Phys Chem Chem Phys 2023; 25:5785-5794. [PMID: 36744652 DOI: 10.1039/d2cp05442f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
High-quality Mn2-xCrxSb (x = 0.01, 0.04, and 0.1) epitaxial thin films were grown on SrTiO3 (STO) (001) single-crystal substrates using molecular beam epitaxy. Magnetotransport and magnetic measurements reveal that the x = 0.01 sample undergoes a quasi-ferrimagnetic (I) [Q-FIM(I)]-to-ferrimagnetic (II) [FIM(II)] spin reorientation (SR) transition and a giant magnetoresistance (MR) associated first-order ferrimagnetic(II)-to-antiferromagnetic (AFM) phase transition upon cooling, resulting in the AFM ground state with a weak in-plane net moment. Upon increasing the doping level from x = 0.01 to 0.1, both the SR transition and the first-order magnetic transition are suppressed. For x = 0.1, the former transition is suppressed, leaving only the Q-FIM(I)-to-AFM transition within the whole temperature region. TAFM-FIM shows almost similar changes upon the application of either in-plane or out-of-plane magnetic fields. TAFM-FIM values of the x = 0.01 and 0.04 samples are much higher than those of the Mn2-xCrxSb bulk with similar doping levels, which can be understood by the clamping effect from STO substrates. For each thin-film sample, the MR effect is observed near TAFM-FIM and disappears in the high temperature Q-FIM(I) phase and low temperature AFM phase, indicating that MR is related to the spin-dependent electron scattering during the first-order magnetic phase transition. Based on the magnetotransport and magnetic data, a magnetic phase diagram is established for the Mn2-xCrxSb films in the low doping level region.
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Affiliation(s)
- Ting-Wei Chen
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Shuang-Shuang Li
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Fang Tang
- Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500, China
| | - Jing-Shi Ying
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Ying Zhang
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Zhao-Cai Wang
- School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Shu-Juan Zhang
- School of Materials and Mechanic & Electrical Engineering, Jiangxi Science and Technology Normal University, Nanchang 330038, China
| | - Fu-Sheng Luo
- School of Physics and Electronic Information, Gannan Normal University, China
| | - Lei Chen
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
| | - Yong Fang
- Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500, China
| | - Ren-Kui Zheng
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
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Zhang SJ, Yan JM, Tang F, Wu J, Dong WQ, Zhang DW, Luo FS, Chen L, Fang Y, Zhang T, Chai Y, Zhao W, Wang X, Zheng RK. Colossal Magnetoresistance in Ti Lightly Doped Cr 2Se 3 Single Crystals with a Layered Structure. ACS Appl Mater Interfaces 2021; 13:58949-58955. [PMID: 34854300 DOI: 10.1021/acsami.1c18848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Stoichiometric Cr2Se3 single crystals are particular layer-structured antiferromagnets, which possess a noncollinear spin configuration, weak ferromagnetic moments, moderate magnetoresistance (MR ∼14.3%), and poor metallic conductivity below the antiferromagnetic phase transition. Here, we report an interesting >16 000% colossal magnetoresistance (CMR) effect in Ti (1.5 atomic percent) lightly doped Cr2Se3 single crystals. Such a CMR is approximately 1143 times larger than that of the stoichiometric Cr2Se3 crystals and is rarely observed in layered antiferromagnets and is attributed to the frustrated spin configuration. Moreover, the Ti doping not only dramatically changes the electronic conductivity of the Cr2Se3 crystal from a bad metal to a semiconductor with a gap of ∼15 meV but also induces a change in the magnetic anisotropy of the Cr2Se3 crystal from strong out-of-plane to weak in-plane. Further, magnetotransport measurements reveal that the low-field MR scales with the square of the reduced magnetization, which is a signature of CMR materials. The layered Ti:Cr2Se3 with the CMR effect could be used as two-dimensional (2D) heterostructure building blocks to provide colossal negative MR in spintronic devices.
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Affiliation(s)
- Shu-Juan Zhang
- School of Materials Science and Engineering and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
- School of Materials and Mechanic & Electrical Engineering, Jiangxi Science and Technology Normal University, Nanchang 330038, China
| | - Jian-Min Yan
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - F Tang
- Jiangsu Laboratory of Advanced Functional Materials and Department of Physics, Changshu Institute of Technology, Changshu 215500, China
| | - Jin Wu
- School of Materials Science and Engineering and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Wei-Qi Dong
- School of Materials Science and Engineering and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Dan-Wen Zhang
- School of Materials Science and Engineering and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Fu-Sheng Luo
- School of Materials Science and Engineering and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Lei Chen
- School of Materials Science and Engineering and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
| | - Y Fang
- Jiangsu Laboratory of Advanced Functional Materials and Department of Physics, Changshu Institute of Technology, Changshu 215500, China
| | - Tao Zhang
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China
| | - Yang Chai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Weiyao Zhao
- Institute for Superconducting and Electronic Materials & ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Innovation Campus, University of Wollongong, North Wollongong, NSW 2500, Australia
| | - Xiaolin Wang
- Institute for Superconducting and Electronic Materials & ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Innovation Campus, University of Wollongong, North Wollongong, NSW 2500, Australia
| | - Ren-Kui Zheng
- School of Materials Science and Engineering and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
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Yang J, Song ZY, Guo L, Gao H, Dong Z, Yu Q, Zheng RK, Kang TT, Zhang K. Nontrivial Giant Linear Magnetoresistance in Nodal-Line Semimetal ZrGeSe 2D Layers. Nano Lett 2021; 21:10139-10145. [PMID: 34543026 DOI: 10.1021/acs.nanolett.1c01647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Linear magnetoresistance (LMR) is usually observed in topological quantum materials and plausibly connected with the topologically nontrivial surface state with Dirac-cone-like linear dispersion because the frequently encountered large Hall resistivity can be trivially mixed into the LMR via charge inhomogeneity. Herein, by applying an optimal gate voltage to nodal-line semimetal ZrGeSe two-dimensional (2D) layers with specific thicknesses, we observe a giant nonsaturated LMR of 8 × 104% at 2 K and a magnetic field of 9 T. This giant LMR is accompanied by a very small Hall resistivity, which is inconsistent with the charge inhomogeneity mechanism. Our systematic results confirm that the giant LMR is maximized when the topological semimetal is in the "even-metal" regime and suppressed upon evolution to the normal "odd-metal" regime. The "even-to-odd" transition is universal regardless of the thicknesses of the crystals. A comparison with Abrikosov's quantum LMR theory indicates that the observed LMR cannot be trivial.
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Affiliation(s)
- Jie Yang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applications, i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Zhi-Yong Song
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, People's Republic of China
| | - Lei Guo
- School of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | - Heng Gao
- International Centre for Quantum and Molecular Structures, Department of Physics, Shanghai University, Shanghai 200444, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Zhuo Dong
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applications, i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Qiang Yu
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applications, i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Ren-Kui Zheng
- School of Materials Science and Engineering, Nanchang University, Nanchang 330031, People's Republic of China
| | - Ting-Ting Kang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, People's Republic of China
| | - Kai Zhang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applications, i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
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9
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Wu J, Zhang CL, Yan JM, Chen L, Guo L, Chen TW, Gao GY, Fei L, Zhao W, Chai Y, Zheng RK. Magnetotransport and magnetic properties of the layered noncollinear antiferromagnetic Cr 2Se 3single crystals. J Phys Condens Matter 2020; 32:475801. [PMID: 32870812 DOI: 10.1088/1361-648x/abaeab] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 08/12/2020] [Indexed: 06/11/2023]
Abstract
We report on the growth of high-quality stoichiometric layered Cr2Se3single crystals with metallic and noncollinear antiferromagnetic ground state using the chemical vapor transport (CVT) method. The crystals show weak ferromagnetism in the in-plane and out-of-plane directions below the Neél temperature (TN), however, the field-cooled out-of-plane magnetization at 500 Oe and 10 K (∼0.24μB/f.u.) is approximately 15 times larger than that of the in-plane one, indicating strongc-axis easy uniaxial magnetic anisotropy, which is further supported by the in-plane and out-of-plane isothermal anisotropic magnetic hysteresis loops and the angular dependent magnetoresistance (MR). The latter also reveals a decrease of the coercive field of the crystal upon the tilting of the weak ferromagnetic easy axis away from the direction of the magnetic field. Further, the out-of-plane isothermal MR are negative belowTNand show butterfly shapes forT< 10 K and couple with the magnetic hysteresisM(H) loop. These results may help researchers better understand the interplay between the weak ferromagnetism and the magnetotransport properties of 2D itinerant noncollinear antiferromagnetic systems.
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Affiliation(s)
- Jin Wu
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang 330031, People's Republic of China
| | - Chuan-Lin Zhang
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang 330031, People's Republic of China
| | - Jian-Min Yan
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Lei Chen
- Institute for Superconducting and Electronic Materials, Innovation Campus, University of Wollongong, Wollongong, NSW 2500, Australia
| | - Lei Guo
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Ting-Wei Chen
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang 330031, People's Republic of China
| | - Guan-Yin Gao
- Hefei National Laboratory for Physical Sciences, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Linfeng Fei
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang 330031, People's Republic of China
| | - Weiyao Zhao
- Institute for Superconducting and Electronic Materials, Innovation Campus, University of Wollongong, Wollongong, NSW 2500, Australia
| | - Yang Chai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, People's Republic of China
| | - Ren-Kui Zheng
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang 330031, People's Republic of China
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
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10
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Guo L, Zhao W, Ding N, Shi XY, Xu M, Chen L, Gao GY, Dong S, Zheng RK. Magnetotransport properties of square-net compounds of NbSiSb and NbGeSb single crystals. J Phys Condens Matter 2020; 32:435701. [PMID: 32634789 DOI: 10.1088/1361-648x/aba385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 07/07/2020] [Indexed: 06/11/2023]
Abstract
We successfully grew single crystals of Si- and Ge-square-net compounds of NbSiSb and NbGeSb whose excellent crystalline quality are verified using single-crystal x-ray diffractionθ-2θscans, rocking curves, scanning and transmission electron microscopies. Since these two compounds share major crystallographic similarity with the topological nodal-line semimetals of ZrSiS family, we employ density functional theory (DFT) calculations and magnetotransport measurements to demonstrate their band structures as well as the electron scattering mechanisms. DFT calculations show that the fermiology displays strong anisotropy from the crystallographicc-axis to theab-plane and weak anisotropy within theabplane, which is consistent with the strong anisotropic magnetotransport behaviors. Following the Kohler's scaling rule we prove that similar interband and intraband electron-phonon scattering mechanisms work in both the NbSiSb and NbGeSb compounds. The study of electronic transport mechanism in the presence of external magnetic field renders deep insight into topological behavior together with its Fermi surface, and the high similarity of crystallography and strong difference in band structures between the present single crystals and that of ZrSiS family provides the possibility to tune the band structure via element doping.
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Affiliation(s)
- Lei Guo
- School of Physics, Southeast University, Nanjing 211189, People's Republic of China
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Weiyao Zhao
- Institute for Superconducting & Electronic Materials, Innovation Campus, University of Wollongong, Wollongong, NSW 2500, Australia
| | - Ning Ding
- School of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | - Xin-Yao Shi
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Meng Xu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Lei Chen
- Institute for Superconducting & Electronic Materials, Innovation Campus, University of Wollongong, Wollongong, NSW 2500, Australia
| | - Guan-Yin Gao
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Shuai Dong
- School of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | - Ren-Kui Zheng
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
- School of Materials Science and Engineering and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China
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11
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Shu L, Ke S, Fei L, Huang W, Wang Z, Gong J, Jiang X, Wang L, Li F, Lei S, Rao Z, Zhou Y, Zheng RK, Yao X, Wang Y, Stengel M, Catalan G. Photoflexoelectric effect in halide perovskites. Nat Mater 2020; 19:605-609. [PMID: 32313265 DOI: 10.1038/s41563-020-0659-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 03/06/2020] [Indexed: 05/28/2023]
Abstract
Harvesting environmental energy to generate electricity is a key scientific and technological endeavour of our time. Photovoltaic conversion and electromechanical transduction are two common energy-harvesting mechanisms based on, respectively, semiconducting junctions and piezoelectric insulators. However, the different material families on which these transduction phenomena are based complicate their integration into single devices. Here we demonstrate that halide perovskites, a family of highly efficient photovoltaic materials1-3, display a photoflexoelectric effect whereby, under a combination of illumination and oscillation driven by a piezoelectric actuator, they generate orders of magnitude higher flexoelectricity than in the dark. We also show that photoflexoelectricity is not exclusive to halides but a general property of semiconductors that potentially enables simultaneous electromechanical and photovoltaic transduction and harvesting in unison from multiple energy inputs.
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Affiliation(s)
- Longlong Shu
- School of Materials Science and Engineering, Nanchang University, Nanchang, People's Republic of China.
| | - Shanming Ke
- School of Materials Science and Engineering, Nanchang University, Nanchang, People's Republic of China
| | - Linfeng Fei
- School of Materials Science and Engineering, Nanchang University, Nanchang, People's Republic of China
| | - Wenbin Huang
- The State Key Lab of Mechanical Transmissions, Chongqing University, Chongqing, People's Republic of China
| | - Zhiguo Wang
- The State Key Lab of Mechanical Transmissions, Chongqing University, Chongqing, People's Republic of China
| | - Jinhui Gong
- School of Materials Science and Engineering, Nanchang University, Nanchang, People's Republic of China
| | - Xiaoning Jiang
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, USA
| | - Li Wang
- School of Materials Science and Engineering, Nanchang University, Nanchang, People's Republic of China
| | - Fei Li
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiao Tong University, Xi'an, People's Republic of China
| | - Shuijin Lei
- School of Materials Science and Engineering, Nanchang University, Nanchang, People's Republic of China
| | - Zhenggang Rao
- School of Materials Science and Engineering, Nanchang University, Nanchang, People's Republic of China
| | - Yangbo Zhou
- School of Materials Science and Engineering, Nanchang University, Nanchang, People's Republic of China
| | - Ren-Kui Zheng
- School of Materials Science and Engineering, Nanchang University, Nanchang, People's Republic of China
| | - Xi Yao
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiao Tong University, Xi'an, People's Republic of China
| | - Yu Wang
- School of Materials Science and Engineering, Nanchang University, Nanchang, People's Republic of China
| | - Massimiliano Stengel
- Institucio Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Catalonia
- Institut de Ciencia de Materials de Barcelona (ICMAB), Consejo Superior de Investigaciones Científicas (CSIC), Campus Universitat Autonoma de Barcelona, Barcelona, Catalonia
| | - Gustau Catalan
- Institucio Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Catalonia.
- Institut Catala de Nanociencia i Nanotecnologia (ICN2), Consejo Superior de Investigaciones Científicas and The Barcelona Institute of Science and Technology (CSIC-BIST), Campus Universitat Autonoma de Barcelona, Barcelona, Catalonia.
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12
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Xu M, Yan JM, Guo L, Wang H, Xu ZX, Yan MY, Lu YL, Gao GY, Li XG, Luo HS, Chai Y, Zheng RK. Nonvolatile Control of the Electronic Properties of In 2-xCr xO 3 Semiconductor Films by Ferroelectric Polarization Charge. ACS Appl Mater Interfaces 2019; 11:32449-32459. [PMID: 31405273 DOI: 10.1021/acsami.9b07967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A series of Cr-doped In2-xCrxO3 (ICO) semiconductor thin films were epitaxially grown on (111)-oriented 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-0.29PT) single-crystal substrates by the pulsed laser deposition. Upon the application of an electric field to the PMN-0.29PT substrate along the thickness direction, we realized in situ, reversible, and nonvolatile control of the electronic properties and Fermi level of the films, which are manifested by abundant physical phenomena such as the n-type to p-type transformation, metal-semiconductor transition, metal-insulator transition, crossover of the magnetoresistance (MR) from negative to positive, and a large nonvolatile on-and-off ratio of 5.5 × 104% at room temperature. We also strictly disclose that both the sign and the magnitude of MR are determined by the electron carrier density of ICO films, which could modify the s-d exchange interaction and weak localization effect. Our results demonstrate that the ferroelectric gating approach using PMN-PT can be utilized to gain deeper insight into the carrier-density-related electronic properties of In2O3-based semiconductors and provide a simple and energy efficient way to construct multifunctional devices which can utilize the unique properties of composite materials.
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Affiliation(s)
- Meng Xu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Jian-Min Yan
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Lei Guo
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Hui Wang
- School of Materials Science and Engineering and Jiangxi Key Laboratory for Two-Dimensional Materials and Devices , Nanchang University , Nanchang 330031 , China
| | - Zhi-Xue Xu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Ming-Yuan Yan
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Yun-Long Lu
- Faculty of Electrical Engineering and Computer Science , Ningbo University , Ningbo 315211 , China
| | - Guan-Yin Gao
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures , University of Science and Technology of China , Hefei 230026 , China
| | - Xiao-Guang Li
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures , University of Science and Technology of China , Hefei 230026 , China
| | - Hao-Su Luo
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Yang Chai
- Department of Applied Physics , The Hong Kong Polytechnic University , Kowloon , Hong Kong , China
| | - Ren-Kui Zheng
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
- School of Materials Science and Engineering and Jiangxi Key Laboratory for Two-Dimensional Materials and Devices , Nanchang University , Nanchang 330031 , China
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13
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Yan JM, Xu ZX, Chen TW, Xu M, Zhang C, Zhao XW, Liu F, Guo L, Yan SY, Gao GY, Wang FF, Zhang JX, Dong SN, Li XG, Luo HS, Zhao W, Zheng RK. Nonvolatile and Reversible Ferroelectric Control of Electronic Properties of Bi 2Te 3 Topological Insulator Thin Films Grown on Pb(Mg 1/3Nb 2/3)O 3-PbTiO 3 Single Crystals. ACS Appl Mater Interfaces 2019; 11:9548-9556. [PMID: 30724082 DOI: 10.1021/acsami.8b20406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Single-phase (00 l)-oriented Bi2Te3 topological insulator thin films have been deposited on (111)-oriented ferroelectric 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-PT) single-crystal substrates. Taking advantage of the nonvolatile polarization charges induced by the polarization direction switching of PMN-PT substrates at room temperature, the carrier density, Fermi level, magnetoconductance, conductance channel, phase coherence length, and quantum corrections to the conductance can be in situ modulated in a reversible and nonvolatile manner. Specifically, upon the polarization switching from the positively poled Pr+ state (i.e., polarization direction points to the film) to the negatively poled Pr- (i.e., polarization direction points to the bottom electrode) state, both the electron carrier density and the Fermi wave vector decrease significantly, reflecting a shift of the Fermi level toward the Dirac point. The polarization switching from Pr+ to Pr- also results in significant increase of the conductance channel α from -0.15 to -0.3 and a decrease of the phase coherence length from 200 to 80 nm at T = 2 K as well as a reduction of the electron-electron interaction. All these results demonstrate that electric-voltage control of physical properties using PMN-PT as both substrates and gating materials provides a simple and a straightforward approach to realize reversible and nonvolatile tuning of electronic properties of topological thin films and may be further extended to study carrier density-related quantum transport properties of other quantum matter.
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Affiliation(s)
- Jian-Min Yan
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Zhi-Xue Xu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Ting-Wei Chen
- School of Materials Science and Engineering , Nanchang University, and Jiangxi Engineering Laboratory for Advanced Functional Thin Films , Nanchang 330031 , China
| | - Meng Xu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Chao Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures , University of Science and Technology of China , Hefei 230026 , China
| | - Xu-Wen Zhao
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Fei Liu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Lei Guo
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Shu-Ying Yan
- Department of Physics , Beijing Normal University , Beijing 100875 , China
| | - Guan-Yin Gao
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures , University of Science and Technology of China , Hefei 230026 , China
| | - Fei-Fei Wang
- Key Laboratory of Optoelectronic Material and Device, Department of Physics , Shanghai Normal University , Shanghai 200234 , China
| | - Jin-Xing Zhang
- Department of Physics , Beijing Normal University , Beijing 100875 , China
| | - Si-Ning Dong
- Department of Physics , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Xiao-Guang Li
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures , University of Science and Technology of China , Hefei 230026 , China
| | - Hao-Su Luo
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Weiyao Zhao
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
- ISEM, Innovation Campus , University of Wollongong , Wollongong , New South Wales 2500 , Australia
| | - Ren-Kui Zheng
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
- School of Materials Science and Engineering , Nanchang University, and Jiangxi Engineering Laboratory for Advanced Functional Thin Films , Nanchang 330031 , China
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14
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Xie L, Guo L, Yu W, Kang T, Zheng RK, Zhang K. Ultrasensitive negative photoresponse in 2D Cr 2Ge 2Te 6 photodetector with light-induced carrier trapping. Nanotechnology 2018; 29:464002. [PMID: 30179161 DOI: 10.1088/1361-6528/aaded6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Cr2Ge2Te6, a layered ferromagnetic semiconductor, has triggered extensive research interest due to its fantastic ferromagnetism and semiconducting characteristics as well as potential applications in next-generation spintronic and nanoelectronic devices. On the basis of its ferromagnetism, combined with rich electronic and optical properties, Cr2Ge2Te6 could be a promising candidate for optoelectronics including magnetophotonics and photodetectors. However, there are no relevant studies addressing this to date. In this work, we comprehensively investigated the photoresponse characteristics of few-layer Cr2Ge2Te6-based detectors. An uncommon negative photoconductivity (NPC) and correlated mechanism are explored with the Cr2Ge2Te6 photodetector. It is found that, both NPC and positive photoconductivity (PPC) may exist in an individual Cr2Ge2Te6 device, which are adjustable by control of the incident light intensity. More significantly, the NPC behavior enables ultrasensitive photoresponses of the Cr2Ge2Te6 photodetectors, where the detection of a weak light with an incident power intensity as low as 0.04 pW and a high responsivity of 340 AW-1 is achieved. This extraordinary performance demonstrates that the two-dimensional (2D) Cr2Ge2Te6 holds great promise for applications in ultraweak light detection.
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Affiliation(s)
- Liu Xie
- School of Nano Technology and Nano Bionics, University of Science and Technology of China, Hefei 230026, Anhui, People's Republic of China. Key Laboratory of Nanodevices and Applications, i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, Jiangsu, People's Republic of China
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15
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Xu ZX, Yan JM, Xu M, Guo L, Chen TW, Gao GY, Dong SN, Zheng M, Zhang JX, Wang Y, Li XG, Luo HS, Zheng RK. Integration of Oxide Semiconductor Thin Films with Relaxor-Based Ferroelectric Single Crystals with Large Reversible and Nonvolatile Modulation of Electronic Properties. ACS Appl Mater Interfaces 2018; 10:32809-32817. [PMID: 30156403 DOI: 10.1021/acsami.8b09170] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report the fabrication of 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-0.29PT)-based ferroelectric field effect transistors (FeFETs) by the epitaxial growth of cobalt-doped tin dioxide (SnO2) semiconductor thin films on PMN-0.29PT single crystals. Using such FeFETs we realized in situ, reversible, and nonvolatile manipulation of the electron carrier density and achieved a large nonvolatile modulation of the resistance (∼330%) of the SnO2:Co films through the polarization switching of PMN-0.29PT at 300 K. Particularly, combining the ferroelectric gating with piezoresponse force microscopy, X-ray diffraction, Hall effect, and magnetoresistance (MR), we rigorously disclose that both sign and magnitude of the MR are intrinsically determined by the electron carrier density, which could modify the s-d exchange interaction of the SnO2:Co films. Furthermore, we realized multilevel resistance states of the SnO2:Co films by combining the ferroelectric gating with ultraviolet light illumination, demonstrating that the FeFETs have potential applications in multistate resistive memories and electro-optical devices.
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Affiliation(s)
- Zhi-Xue Xu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Jian-Min Yan
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Meng Xu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Lei Guo
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Ting-Wei Chen
- School of Materials Science and Engineering , Nanchang University , Nanchang 330031 , China
| | - Guan-Yin Gao
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures , University of Science and Technology of China , Hefei 230026 , China
| | - Si-Ning Dong
- Department of Physics , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Ming Zheng
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Jin-Xing Zhang
- Department of Physics , Beijing Normal University , Beijing 100875 , China
| | - Yu Wang
- School of Materials Science and Engineering , Nanchang University , Nanchang 330031 , China
| | - Xiao-Guang Li
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures , University of Science and Technology of China , Hefei 230026 , China
| | - Hao-Su Luo
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Ren-Kui Zheng
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
- School of Materials Science and Engineering , Nanchang University , Nanchang 330031 , China
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16
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Saadaoui H, Luo X, Salman Z, Cui XY, Bao NN, Bao P, Zheng RK, Tseng LT, Du YH, Prokscha T, Suter A, Liu T, Wang YR, Li S, Ding J, Ringer SP, Morenzoni E, Yi JB. Intrinsic Ferromagnetism in the Diluted Magnetic Semiconductor Co:TiO_{2}. Phys Rev Lett 2016; 117:227202. [PMID: 27925730 DOI: 10.1103/physrevlett.117.227202] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Indexed: 06/06/2023]
Abstract
Here we present a study of magnetism in Co_{0.05}Ti_{0.95}O_{2-δ} anatase films grown by pulsed laser deposition under a variety of oxygen partial pressures and deposition rates. Energy-dispersive spectrometry and transmission electron microscopy analyses indicate that a high deposition rate leads to a homogeneous microstructure, while a very low rate or postannealing results in cobalt clustering. Depth resolved low-energy muon spin rotation experiments show that films grown at a low oxygen partial pressure (≈10^{-6} torr) with a uniform structure are fully magnetic, indicating intrinsic ferromagnetism. First principles calculations identify the beneficial role of low oxygen partial pressure in the realization of uniform carrier-mediated ferromagnetism. This work demonstrates that Co:TiO_{2} is an intrinsic diluted magnetic semiconductor.
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Affiliation(s)
- H Saadaoui
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - X Luo
- School of Materials Science and Engineering, UNSW, Sydney, New South Wales 2052, Australia
| | - Z Salman
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - X Y Cui
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - N N Bao
- Department of Materials Science and Engineering, National University of Singapore, 119260, Singapore
| | - P Bao
- School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - R K Zheng
- School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - L T Tseng
- School of Materials Science and Engineering, UNSW, Sydney, New South Wales 2052, Australia
| | - Y H Du
- Institute of Chemical and Engineering Science, Agency for Science, Technology and Research (A*STAR), 1 Pesek Road, Jurong Island, 627833, Singapore
| | - T Prokscha
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - A Suter
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - T Liu
- ANKA, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Y R Wang
- School of Materials Science and Engineering, UNSW, Sydney, New South Wales 2052, Australia
| | - S Li
- School of Materials Science and Engineering, UNSW, Sydney, New South Wales 2052, Australia
| | - J Ding
- Department of Materials Science and Engineering, National University of Singapore, 119260, Singapore
| | - S P Ringer
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales 2006, Australia
- The Australian Institute for Nanoscale Science and Technology, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - E Morenzoni
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - J B Yi
- School of Materials Science and Engineering, UNSW, Sydney, New South Wales 2052, Australia
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17
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Chen L, Zhao WY, Wang J, Gao GY, Zhang JX, Wang Y, Li XM, Cao SX, Li XG, Luo HS, Zheng RK. Semiconductor/Piezoelectrics Hybrid Heterostructures with Highly Effective Gate-Tunable Electrotransport and Magnetic Behaviors. ACS Appl Mater Interfaces 2016; 8:26932-26937. [PMID: 27633004 DOI: 10.1021/acsami.6b07814] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report the epitaxial growth of oxygen deficient titanium dioxide thin films on 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) single crystals and realized highly effective in situ electrostatic manipulation of electrotransport and magnetism of TiO2-δ films via gate voltages. Upon the polarization switching in the PMN-PT, the carrier density of the TiO2-δ film could be reversibly modified, resulting in a large nonvolatile resistivity modulation by ∼51% at T = 300 K, approximately 4-12 times larger than that of other transition-metal oxide film/PMN-PT structures. By taking advantage of in situ manipulation of the carrier density via gate voltages, we found that competition between the trap of electrons by the Ti3+-VO pairs and that by the positive polarization charges at the interface results in a significant resistivity relaxation upon the polarization switching, and revealed that magnetization is inversely correlated with the carrier density of the TiO2-δ film. Such hybrid structures combining materials with dissimilar functionalities may have potential applications in multifunctional devices which can take advantage of the useful and unique properties of both materials.
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Affiliation(s)
- Lei Chen
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
- Department of Physics, Shanghai University , Shanghai 200444, China
| | - Wei-Yao Zhao
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
- Department of Physics, Shanghai University , Shanghai 200444, China
| | - Jing Wang
- Department of Physics, Beijing Normal University , Beijing 100875, China
| | - Guan-Yin Gao
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Physics, University of Science and Technology of China , Hefei 230026, China
| | - Jin-Xing Zhang
- Department of Physics, Beijing Normal University , Beijing 100875, China
| | - Yu Wang
- School of Materials Science and Engineering, Nanchang University , Nanchang 330031, China
| | - Xiao-Min Li
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
| | - Shi-Xun Cao
- Department of Physics, Shanghai University , Shanghai 200444, China
| | - Xiao-Guang Li
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Physics, University of Science and Technology of China , Hefei 230026, China
- Collaborative Innovation Center of Advanced Microstructures , Nanjing 210093, China
| | - Hao-Su Luo
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
| | - Ren-Kui Zheng
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
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18
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Lv Y, Chen J, Zheng RK, Song J, Zhang T, Li X, Shi X, Chen L. Photo-induced enhancement of the power factor of Cu2S thermoelectric films. Sci Rep 2015; 5:16291. [PMID: 26573407 PMCID: PMC4647207 DOI: 10.1038/srep16291] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 09/28/2015] [Indexed: 12/02/2022] Open
Abstract
Element doping is commonly used to adjust the carrier concentrations in semiconductors such as thermoelectric materials. However, the doping process unavoidably brings in defects or distortions in crystal lattices, which further strongly affects the physical properties of the materials. In this work, high energy photons have been used to activate the carriers in Cu2S thermoelectric films. As a result, the carrier concentrations, and the respective electrical conductivity as well as Seebeck coefficient are further changed. The photon-induced electrical transport properties are further analyzed utilizing a Parallel circuit model. Due to the realization of optimized carrier concentrations by photon activation, the power factor of Cu2S film is improved more than 900 times as compared with the dark data. As compared to the traditional doping process, the approach using photon activation can realize the tuning of carrier concentrations without affecting crystal lattice. This method provides an opportunity to investigate the intrinsic physical properties of semiconductor materials without involving traditional element doping process that usually brings in additional lattice defects or distortions.
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Affiliation(s)
- Yanhong Lv
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China.,CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China.,Univerisity of Chinese Academy of Sciences, Beijing 100049, China
| | - Jikun Chen
- CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China.,School of Materials Science and Engineering, University of Science and Technology of Beijing, Beijing, China
| | - Ren-Kui Zheng
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
| | - Junqiang Song
- CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China
| | - Tiansong Zhang
- CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China
| | - Xiaomin Li
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
| | - Xun Shi
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China.,CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China
| | - Lidong Chen
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China.,CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China
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19
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Shi L, Li Y, Wu C, Zheng RK. Preparation and Photoelectric and Magnetic Properties of Cu2MnSnS4Nanosheets. Chempluschem 2015; 80:1537-1540. [DOI: 10.1002/cplu.201500163] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Liang Shi
- Department of Chemistry; University of Science and Technology of China; Hefei 230026 P. R. China
| | - Yanan Li
- Department of Chemistry; University of Science and Technology of China; Hefei 230026 P. R. China
| | - Chunyan Wu
- Department of Chemistry; University of Science and Technology of China; Hefei 230026 P. R. China
| | - Ren-Kui Zheng
- State Key Laboratory of High Performance Ceramics and; Superfine Microstructure, Shanghai Institute of Ceramics; Chinese Academy of Sciences; Shanghai 200050 P. R. China
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20
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Yeoh WK, Cui XY, Gault B, De Silva KSB, Xu X, Liu HW, Yen HW, Wong D, Bao P, Larson DJ, Martin I, Li WX, Zheng RK, Wang XL, Dou SX, Ringer SP. On the roles of graphene oxide doping for enhanced supercurrent in MgB2 based superconductors. Nanoscale 2014; 6:6166-6172. [PMID: 24793305 DOI: 10.1039/c4nr00415a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Due to their graphene-like properties after oxygen reduction, incorporation of graphene oxide (GO) sheets into correlated-electron materials offers a new pathway for tailoring their properties. Fabricating GO nanocomposites with polycrystalline MgB2 superconductors leads to an order of magnitude enhancement of the supercurrent at 5 K/8 T and 20 K/4 T. Herein, we introduce a novel experimental approach to overcome the formidable challenge of performing quantitative microscopy and microanalysis of such composites, so as to unveil how GO doping influences the structure and hence the material properties. Atom probe microscopy and electron microscopy were used to directly image the GO within the MgB2, and we combined these data with computational simulations to derive the property-enhancing mechanisms. Our results reveal synergetic effects of GO, namely, via localized atomic (carbon and oxygen) doping as well as texturing of the crystals, which provide both inter- and intra-granular flux pinning. This study opens up new insights into how low-dimensional nanostructures can be integrated into composites to modify the overall properties, using a methodology amenable to a wide range of applications.
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Affiliation(s)
- W K Yeoh
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, New South Wales 2006, Australia.
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21
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Zheng M, Zhu QX, Li XY, Li XM, Zheng RK. Magnetic and electrical properties of three-dimensional (La,Pr,Ca)MnO3 nanofilm/ZnO nanorod p–n junctions. RSC Adv 2014. [DOI: 10.1039/c4ra06302c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Excellent room temperature rectification performance and enhanced ferromagnetic phase transition temperature was achieved for the La0.5Pr0.17Ca0.33MnO3 nanofilm/ZnO nanorod p–n junctions prepared by depositing the La0.5Pr0.17Ca0.33MnO3 shell layer on the ZnO nanorods.
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Affiliation(s)
- Ming Zheng
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure
- Shanghai Institute of Ceramics
- Chinese Academy of Sciences
- Shanghai 200050, China
| | - Qiu-Xiang Zhu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure
- Shanghai Institute of Ceramics
- Chinese Academy of Sciences
- Shanghai 200050, China
| | - Xue-Yan Li
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure
- Shanghai Institute of Ceramics
- Chinese Academy of Sciences
- Shanghai 200050, China
| | - Xiao-Min Li
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure
- Shanghai Institute of Ceramics
- Chinese Academy of Sciences
- Shanghai 200050, China
| | - Ren-Kui Zheng
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure
- Shanghai Institute of Ceramics
- Chinese Academy of Sciences
- Shanghai 200050, China
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22
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Cui XY, Li L, Zheng RK, Liu ZW, Stampfl C, Ringer SP. Graphene based dots and antidots: a comparative study from first principles. J Nanosci Nanotechnol 2013; 13:1251-1255. [PMID: 23646613 DOI: 10.1166/jnn.2013.6118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Graphene based quantum dots and antidots are two nanostructures of primary importance for their fundamental physics and technological applications, particularly in the emerging field of graphene-based nanoelectronics and nanospintronics. Herein, based on first principles density functional theory calculations, we report a comparative study on the electronic structure of these two structurally complementary entities, where the bandgap opening, edge magnetism and the role of hydrogenation are investigated. Our results show the diversity of electronic structures of various dots and antidots, whose properties are sensitive to the edge detailed geometry (including size and shape and edge type). Hydrogen passivation plays an essential roal in affecting the related properties, in particular, it leads to larger bandgap values and suppress the edge magnetism. The frontier orbital analysis is employed to rationalize and compare the complicated nature of dots and antidots. Based on the specific geometrical consideration and the total energy competition of the ground antiferromagnetic and the ferromagnetic states, some magnetic structures (the unpassivated 42-atom-antidot and 54-atom-dot) are proposed to be useful as magnetic switches.
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Affiliation(s)
- X Y Cui
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, New South Wales 2006, Australia
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23
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Gao XD, Li XM, Gan XY, Wu YQ, Zheng RK, Wang CL, Gu ZY, He P. Aerogel based SiO2–TiO2 hybrid photoanodes for enhanced light harvesting in dye-sensitized solar cells. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm33945e] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Yeoh WK, Gault B, Cui XY, Zhu C, Moody MP, Li L, Zheng RK, Li WX, Wang XL, Dou SX, Sun GL, Lin CT, Ringer SP. Direct observation of local potassium variation and its correlation to electronic inhomogeneity in (Ba(1-x)K(x))Fe2As2 pnictide. Phys Rev Lett 2011; 106:247002. [PMID: 21770591 DOI: 10.1103/physrevlett.106.247002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Indexed: 05/31/2023]
Abstract
Local fluctuations in the distribution of dopant atoms are thought to cause the nanoscale electronic disorder or phase separation in pnictide superconductors. Atom probe tomography has enabled the first direct observations of dopant species clustering in a K-doped 122-phase pnictide. First-principles calculations suggest the coexistence of static magnetism and superconductivity on a lattice parameter length scale over a wide range of dopant concentrations. Our results provide evidence for a mixed scenario of phase coexistence and phase separation, depending on local dopant atom distributions.
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Affiliation(s)
- W K Yeoh
- Australian Centre for Microscopy & Microanalysis, University of Sydney, Sydney, New South Wales, Australia.
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25
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Li LY, Cheng YH, Luo XG, Liu H, Wen GH, Zheng RK, Ringer SP. Room-temperature ferromagnetism and the scaling relation between magnetization and average granule size in nanocrystalline Zn/ZnO core-shell structures prepared by sputtering. Nanotechnology 2010; 21:145705. [PMID: 20234078 DOI: 10.1088/0957-4484/21/14/145705] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Ferromagnetism is found in nanocrystalline Zn/ZnO core-shell structures prepared by sputtering pure Zn with subsequent oxidation. The saturation magnetization (M(S)) of the passivated ZnO shells increases with decrease in average particle size (d). The Curie temperature of the samples is above 400 degrees C. It is found that the ferromagnetism has a close relationship with point defects in ZnO shells. The maximum magnetization is estimated to be 28 emu cm(-3) (i.e. 0.14 mu(B) per unit cell) at 300 K, which is over three orders of magnitude larger than that of undoped ZnO nanoparticles or nanorods (10(-3)-10(-2) emu cm(-3)). More importantly, there is a scaling relation of M(s) alpha 1/d(n) (n = 5.20 +/- 0.20) for samples with d <or= 76 nm despite substantial differences in the particle size and shape. The results suggest that defects at the interface of the Zn/ZnO heterostructure make the main magnetic contributions.
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Affiliation(s)
- L Y Li
- Department of Electronics, Nankai University, Tianjin, People's Republic of China
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26
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Zheng RK, Gu H, Xu B, Zhang XX. The origin of the non-monotonic field dependence of the blocking temperature in magnetic nanoparticles. J Phys Condens Matter 2006; 18:5905-5910. [PMID: 21690806 DOI: 10.1088/0953-8984/18/26/010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The dependence of the peak temperature (T(P)) of the zero-field-cooled (ZFC) magnetization curves on the field in a magnetic nanoparticle system was studied using a diluted magnetic fluid composed of FePt nanoparticles. We found that the peak temperature increases with increasing applied field below 3 kOe; it then decreases when the applied field is increased further. We attribute the non-monotonic field dependence of the peak temperature to the anisotropic energy barrier distribution of the particles and to the slow decrease of high-field magnetization above the blocking temperature. Numerical simulations, based on magnetic dynamics, agree well with our experimental results.
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Affiliation(s)
- R K Zheng
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China
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27
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Zheng RK, Yang Y, Wang Y, Wang J, Chan HLW, Choy CL, Jin CG, Li XG. A simple and convenient route to prepare poly(vinylidene fluoride trifluoroethylene) copolymer nanowires and nanotubes. Chem Commun (Camb) 2005:1447-9. [PMID: 15756331 DOI: 10.1039/b417033d] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Poly(vinylidene fluoride trifluoroethylene) copolymer nanowires and nanotubes have been prepared for the first time via a high temperature (</=260 degrees C) vacuum infiltration method, which is a simple and convenient route for fabricating polymer nanowires and nanotubes when polymers, instead of monomers, are used as the starting materials.
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Affiliation(s)
- R K Zheng
- Department of Applied Physics and Materials Research Center, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
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28
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Zheng RK, Gu H, Zhang XX. Comment on "memory effects in an interacting magnetic nanoparticle system". Phys Rev Lett 2004; 93:139702-139703. [PMID: 15524768 DOI: 10.1103/physrevlett.93.139702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2003] [Indexed: 05/24/2023]
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29
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Kou HZ, Gao S, Zhang J, Wen GH, Su G, Zheng RK, Zhang XX. Unexpected assembly of a unique cyano-bridged three-dimensional Cu3Cr2 ferromagnet. J Am Chem Soc 2001; 123:11809-10. [PMID: 11716743 DOI: 10.1021/ja016656p] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- H Z Kou
- State Key Laboratory of Rare Earth Materials, Chemistry and Applications, PKU-HKU Joint Laboratory on Rare Earth Materials and Bioinorganic Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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