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Zhang B, Wu L, Yin WG, Sun CJ, Yang P, Venkatesan T, Chen J, Zhu Y, Chow GM. Interfacial Coupling-Induced Ferromagnetic Insulator Phase in Manganite Film. NANO LETTERS 2016; 16:4174-4180. [PMID: 27276032 DOI: 10.1021/acs.nanolett.6b01056] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Interfaces with subtle differences in atomic and electronic structures in perovskite ABO3 heterostructures often yield intriguingly different properties, yet their exact roles remain elusive. Here, we report an integrated study of unusual transport, magnetic, and structural properties of Pr0.67Sr0.33MnO3 film on SrTiO3 substrate. The variations in the out-of-plane lattice constant and BO6 octahedral rotation across the Pr0.67Sr0.33MnO3/SrTiO3 interface strongly depend on the thickness of the Pr0.67Sr0.33MnO3 film. In the 12 nm film, a new interface-sensitive ferromagnetic polaronic insulator (FI') phase is formed during the cubic-to-tetragonal phase transition of SrTiO3, apparently due to the enhanced electron-phonon interaction and atomic disorder in the film. The transport properties of the FI' phase in the 30 nm film are masked because of the reduced interfacial coupling and smaller interface-to-volume ratio. This work demonstrates how thickness-dependent interfacial coupling leads to the formation of a theoretically predicted ferromagnetic-polaronic insulator, as illustrated in a new phase diagram, that is otherwise ferromagnetic metal (FM) in bulk form.
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Affiliation(s)
- Bangmin Zhang
- Department of Materials Science & Engineering, National University of Singapore , 117576, Singapore
| | - Lijun Wu
- Condensed Matter Physics & Materials Science Division, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Wei-Guo Yin
- Condensed Matter Physics & Materials Science Division, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Cheng-Jun Sun
- Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Ping Yang
- Singapore Synchrotron Light Source (SSLS), National University of Singapore , 5 Research Link, 117603 Singapore
| | - T Venkatesan
- NUSNNI-Nanocore, National University of Singapore , 117411, Singapore
- Department of Physics, National University of Singapore , 117542, Singapore
- Department of Electrical & Computer Engineering, National University of Singapore , 117576, Singapore
| | - Jingsheng Chen
- Department of Materials Science & Engineering, National University of Singapore , 117576, Singapore
| | - Yimei Zhu
- Condensed Matter Physics & Materials Science Division, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Gan Moog Chow
- Department of Materials Science & Engineering, National University of Singapore , 117576, Singapore
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Zhu M, Peng J, Zou T, Prokes K, Mahanti SD, Hong T, Mao ZQ, Liu GQ, Ke X. Colossal Magnetoresistance in a Mott Insulator via Magnetic Field-Driven Insulator-Metal Transition. PHYSICAL REVIEW LETTERS 2016; 116:216401. [PMID: 27284665 DOI: 10.1103/physrevlett.116.216401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Indexed: 06/06/2023]
Abstract
We present a new type of colossal magnetoresistance (CMR) arising from an anomalous collapse of the Mott insulating state via a modest magnetic field in a bilayer ruthenate, Ti-doped Ca_{3}Ru_{2}O_{7}. Such an insulator-metal transition is accompanied by changes in both lattice and magnetic structures. Our findings have important implications because a magnetic field usually stabilizes the insulating ground state in a Mott-Hubbard system, thus calling for a deeper theoretical study to reexamine the magnetic field tuning of Mott systems with magnetic and electronic instabilities and spin-lattice-charge coupling. This study further provides a model approach to search for CMR systems other than manganites, such as Mott insulators in the vicinity of the boundary between competing phases.
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Affiliation(s)
- M Zhu
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - J Peng
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - T Zou
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - K Prokes
- Helmholtz Zentrum Berlin, D-14109 Berlin, Germany
| | - S D Mahanti
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - T Hong
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Z Q Mao
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - G Q Liu
- Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | - X Ke
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
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Avella A, Oleś AM, Horsch P. Defects, Disorder, and Strong Electron Correlations in Orbital Degenerate, Doped Mott Insulators. PHYSICAL REVIEW LETTERS 2015; 115:206403. [PMID: 26613458 DOI: 10.1103/physrevlett.115.206403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Indexed: 06/05/2023]
Abstract
We elucidate the effects of defect disorder and e-e interaction on the spectral density of the defect states emerging in the Mott-Hubbard gap of doped transition-metal oxides, such as Y(1-x)Ca(x)VO(3). A soft gap of kinetic origin develops in the defect band and survives defect disorder for e-e interaction strengths comparable to the defect potential and hopping integral values above a doping dependent threshold; otherwise only a pseudogap persists. These two regimes naturally emerge in the statistical distribution of gaps among different defect realizations, which turns out to be of Weibull type. Its shape parameter k determines the exponent of the power-law dependence of the density of states at the chemical potential (k-1) and hence distinguishes between the soft gap (k≥2) and the pseudogap (k<2) regimes. Both k and the effective gap scale with the hopping integral and the e-e interaction in a wide doping range. The motion of doped holes is confined by the closest defect potential and the overall spin-orbital structure. Such a generic behavior leads to complex nonhydrogenlike defect states that tend to preserve the underlying C-type spin and G-type orbital order and can be detected and analyzed via scanning tunneling microscopy.
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Affiliation(s)
- Adolfo Avella
- Dipartimento di Fisica "E.R. Caianiello," Università degli Studi di Salerno, I-84084 Fisciano (SA), Italy
- CNR-SPIN, UoS di Salerno, I-84084 Fisciano (SA), Italy
- Unità CNISM di Salerno, Università degli Studi di Salerno, I-84084 Fisciano (SA), Italy
| | - Andrzej M Oleś
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
- Marian Smoluchowski Institute of Physics, Jagiellonian University, prof. Łojasiewicza 11, PL-30348 Kraków, Poland
| | - Peter Horsch
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
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Du Y, Wang JO, Jiang L, Borgna LS, Wang Y, Zheng Y, Hu T. Data analysis method to achieve sub-10 pm spatial resolution using extended X-ray absorption fine-structure spectroscopy. JOURNAL OF SYNCHROTRON RADIATION 2014; 21:756-761. [PMID: 24971971 DOI: 10.1107/s1600577514010406] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 05/07/2014] [Indexed: 06/03/2023]
Abstract
Obtaining sub-10 pm spatial resolution by extended X-ray absorption fine structure (EXAFS) spectroscopy is required in many important fields of research, such as lattice distortion studies in colossal magnetic resistance materials, high-temperature superconductivity materials etc. However, based on the existing EXAFS data analysis methods, EXAFS has a spatial resolution limit of π/2Δk which is larger than 0.1 Å. In this paper a new data analysis method which can easily achieve sub-10 pm resolution is introduced. Theoretically, the resolution limit of the method is three times better than that normally available. The method is examined by numerical simulation and experimental data. As a demonstration, the LaFe1-xCrxO3 system (x = 0, 1/3, 2/3) is studied and the structural information of FeO6 octahedral distortion as a function of Cr doping is resolved directly from EXAFS, where a resolution better than 0.074 Å is achieved.
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Affiliation(s)
- Yonghua Du
- Institute of Chemical and Engineering Sciences, A*STAR, Singapore 627833, Singapore
| | - Jia Ou Wang
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Longhua Jiang
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | | | - Yanfei Wang
- Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, People's Republic of China
| | - Yi Zheng
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Tiandou Hu
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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Mukherjee A, Cole WS, Woodward P, Randeria M, Trivedi N. Theory of strain-controlled magnetotransport and stabilization of the ferromagnetic insulating phase in manganite thin films. PHYSICAL REVIEW LETTERS 2013; 110:157201. [PMID: 25167302 DOI: 10.1103/physrevlett.110.157201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Indexed: 06/03/2023]
Abstract
We show that applying strain on half-doped manganites makes it possible to tune the system to the proximity of a metal-insulator transition and thereby generate a colossal magnetoresistance (CMR) response. This phase competition not only allows control of CMR in ferromagnetic metallic manganites but can be used to generate CMR response in otherwise robust insulators at half-doping. Further, from our realistic microscopic model of strain and magnetotransport calculations within the Kubo formalism, we demonstrate a striking result of strain engineering that, under tensile strain, a ferromagnetic charge-ordered insulator, previously inaccessible to experiments, becomes stable.
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Affiliation(s)
- Anamitra Mukherjee
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada and Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - William S Cole
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Patrick Woodward
- Department of Chemistry, The Ohio State University, Columbus, Ohio 43210, USA
| | - Mohit Randeria
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Nandini Trivedi
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
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Fedoseev SA, Pan AV, Rubanov S, Golovchanskiy IA, Shcherbakova OV. Large, controllable spikes of magnetoresistance in La(2/3)Ca(1/3)MnO3/SrTiO3 superlattices. ACS NANO 2013; 7:286-293. [PMID: 23241017 DOI: 10.1021/nn304127n] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have investigated superlattices consisting of up to 30 epitaxial nanomultilayers (3-7 nm thick) of ferromagnetic La(2/3)Ca(1/3)MnO(3) (LCMO) and insulating SrTiO(3) (STO) hybrids. The superlattices demonstrate dramatic shifts of Curie temperature, indicating the possibility of its tunability. The metal-insulator transition (MIT) has been observed around 140 K. Below the MIT temperature, the superlattices have shown sharp drops of resistivity, facilitating the largest and sharpest magnetoresistance peaks (>2000%) ever observed in LCMO films and superlattices at low temperatures. The observed experimental results can be explained in the frame of the phase separation model in manganites with well-organized structures. The results of magnetic and transport measurements of such hybrid structures are discussed, indicating a magnetodielectric effect in STO interlayers. The magnetic and transport properties of the superlattices are shown to be technology-dependent, experiencing dimensional transitions, which enables the creation of structures with prescribed magnetoresistance characteristics for a broad range of applications.
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Affiliation(s)
- Sergey A Fedoseev
- Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
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Gu H, Zhang X, Wei H, Huang Y, Wei S, Guo Z. An overview of the magnetoresistance phenomenon in molecular systems. Chem Soc Rev 2013; 42:5907-43. [DOI: 10.1039/c3cs60074b] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Zhou S, Guo Y, Wang C, He L, Zhao J, Shi L. Magnetic phase diagram of nanosized half-doped manganites: role of size reduction. Dalton Trans 2012; 41:7109-14. [PMID: 22565283 DOI: 10.1039/c2dt00029f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The magnetic properties of ~40 nm Nd(0.5)Ca(0.5)MnO(3) and Sm(0.5)Sr(0.5)MnO(3) nanoparticles are investigated by magnetometry and electronic spin resonance (ESR) spectroscopy. It is found that although their bulk counterparts have quite different magnetic properties at low temperatures, both the nanoparticles exhibit very similar magnetic behaviors, where the charge ordered transitions disappear and weak ferromagnetism emerges below about 100 K. A detailed analysis on the magnetic susceptibilities and the ESR linewidths reveals that for the two compounds the size reduction weakens both the ferromagnetic and antiferromagnetic interactions, and converts the long-range charge orderings to short-range ones. Moreover, the strength of the charge ordered correlations is observed to be not much affected by the size reduction. Based on the present results and the previous studies on various nanosized half-doped manganites, the magnetic phase diagram of the half-doped manganites with the particle sizes of ~25-40 nm is established. We find that this diagram is very similar to those for the bulk near half-doped manganites with large quenched disorder, which allows us to propose that the reported exotic phenomena in the nanosized half-doped manganites should be mainly ascribed to surface disorder effect. These results may provide a deeper insight into the role of size reduction on the physics of half-doped manganites.
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Affiliation(s)
- Shiming Zhou
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
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Singh A, Singh DK. Onset and melting of local orbital order. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:086003. [PMID: 22277731 DOI: 10.1088/0953-8984/24/8/086003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The onset and melting of locally staggered charge/orbital correlations is investigated within a two-orbital correlated electron model with inter-orbital and inter-site Coulomb interactions. The CE-type orbital correlation exhibits a sharp onset close to the Curie temperature and rapid thermal melting thereafter, which provides quantitative understanding of the (π/2,π/2,0) feature observed in neutron scattering experiments on La(0.7)(Ca(y)Sr(1-y))(0.3)MnO(3) single crystals. In the zig-zag AF state, the CE-type orbital correlations are found to be even more readily stabilized, but only within a narrow doping regime around x = 0.5.
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Affiliation(s)
- Avinash Singh
- Department of Physics, Indian Institute of Technology, Kanpur, India
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Rout GC, Panda S, Behera SN. The effect of band Jahn-Teller distortion on the magnetoresistivity of manganites: a model study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:396001. [PMID: 21900738 DOI: 10.1088/0953-8984/23/39/396001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a model study of magnetoresistance through the interplay of magnetisation, structural distortion and external magnetic field for the manganite systems. The manganite system is described by the Hamiltonian which consists of the s-d type double exchange interaction, Heisenberg spin-spin interaction among the core electrons, and the static and dynamic band Jahn-Teller (JT) interaction in the e(g) band. The relaxation time of the e(g) electron is found from the imaginary part of the Green's function using the total Hamiltonian consisting of the interactions due to the electron and phonon. The calculated resistivity exhibits a peak in the pure JT distorted insulating phase separating the low temperature metallic ferromagnetic phase and the high temperature paramagnetic phase. The resistivity is suppressed with the increase of the external magnetic field. The e(g) electron band splitting and its effect on magnetoresistivity is reported here.
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Affiliation(s)
- G C Rout
- Condensed Matter Physics Group, P G Department of Applied Physics and Ballistics, F M University, Balasore 756 019, India.
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