1
|
Mazza AR, Lu Q, Hu G, Li H, Browning JF, Charlton TR, Brahlek M, Ganesh P, Ward TZ, Lee HN, Eres G. Reversible Hydrogen-Induced Phase Transformations in La 0.7Sr 0.3MnO 3 Thin Films Characterized by In Situ Neutron Reflectometry. ACS Appl Mater Interfaces 2022; 14:10898-10906. [PMID: 35170955 DOI: 10.1021/acsami.1c20590] [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: 06/14/2023]
Abstract
We report on the mechanism for hydrogen-induced topotactic phase transitions in perovskite (PV) oxides using La0.7Sr0.3MnO3 as a prototypical example. Hydrogenation starts with lattice expansion confirmed by X-ray diffraction (XRD). The strain- and oxygen-vacancy-mediated electron-phonon coupling in turn produces electronic structure changes that manifest through the appearance of a metal insulator transition accompanied by a sharp increase in resistivity. The ordering of initially randomly distributed oxygen vacancies produces a PV to brownmillerite phase (La0.7Sr0.3MnO2.5) transition. This phase transformation proceeds by the intercalation of oxygen vacancy planes confirmed by in situ XRD and neutron reflectometry (NR) measurements. Despite the prevailing picture that hydrogenation occurs by reaction with lattice oxygen, NR results are not consistent with deuterium (hydrogen) presence in the La0.7Sr0.3MnO3 lattice at steady state. The film can reach a highly oxygen-deficient La0.7Sr0.3MnO2.1 metastable state that is reversible to the as-grown composition simply by annealing in air. Theoretical calculations confirm that hydrogenation-induced oxygen vacancy formation is energetically favorable in La0.7Sr0.3MnO3. The hydrogenation-driven changes of the oxygen sublattice periodicity and the electrical and magnetic properties similar to interface effects induced by oxygen-deficient cap layers persist despite hydrogen not being present in the lattice.
Collapse
Affiliation(s)
- Alessandro R Mazza
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Qiyang Lu
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Guoxiang Hu
- Department of Chemistry and Biochemistry, Queens College, City University of New York, Queens, New York 11367, United States
| | - Haoxiang Li
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - James F Browning
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Timothy R Charlton
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Matthew Brahlek
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Panchapakesan Ganesh
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Thomas Zac Ward
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Ho Nyung Lee
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Gyula Eres
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| |
Collapse
|
2
|
Zhao W, Bi S, Balke N, Rack PD, Ward TZ, Kalinin SV, Dai S, Feng G. Understanding Electric Double-Layer Gating Based on Ionic Liquids: from Nanoscale to Macroscale. ACS Appl Mater Interfaces 2018; 10:43211-43218. [PMID: 30422617 DOI: 10.1021/acsami.8b15199] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In electric double-layer transistors (EDLTs), it is well known that the EDL formed by ionic liquids (ILs) can induce an ultrahigh carrier density at the semiconductor surface, compared to solid dielectric. However, the mechanism of device performance is still not fully understood, especially at a molecular level. Here, we evaluate the gating performance of amorphous indium gallium zinc oxide (a-IGZO) transistor coupled with a series of imidazolium-based ILs, using an approach combining of molecular dynamics simulation and finite element modeling. Results reveal that the EDL with different ion structures could produce inhomogeneous electric fields at the solid-electrolyte interface, and the heterogeneity of electric field-induced charge distributions at semiconductor surface could reduce the electrical conductance of a-IGZO during gating process. Meanwhile, a resistance network analysis was adopted to bridge the nanoscopic data with the macroscopic transfer characteristics of IL-gated transistor, and showed that our theoretical results could well estimate the gating performance of practical devices. Thereby, our findings could provide both new concepts and modeling techniques for IL-gated transistors.
Collapse
Affiliation(s)
- Wei Zhao
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Sheng Bi
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering , Huazhong University of Science and Technology , Wuhan 430074 , China
| | | | | | | | | | | | - Guang Feng
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering , Huazhong University of Science and Technology , Wuhan 430074 , China
| |
Collapse
|
3
|
Black JM, Come J, Bi S, Zhu M, Zhao W, Wong AT, Noh JH, Pudasaini PR, Zhang P, Okatan MB, Dai S, Kalinin SV, Rack PD, Ward TZ, Feng G, Balke N. Role of Electrical Double Layer Structure in Ionic Liquid Gated Devices. ACS Appl Mater Interfaces 2017; 9:40949-40958. [PMID: 29063758 DOI: 10.1021/acsami.7b11044] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ionic liquid gating of transition metal oxides has enabled new states (magnetic, electronic, metal-insulator), providing fundamental insights into the physics of strongly correlated oxides. However, despite much research activity, little is known about the correlation of the structure of the liquids in contact with the transition metal oxide surface, its evolution with the applied electric potential, and its correlation with the measured electronic properties of the oxide. Here, we investigate the structure of an ionic liquid at a semiconducting oxide interface during the operation of a thin film transistor where the electrical double layer gates the device using experiment and theory. We show that the transition between the ON and OFF states of the amorphous indium gallium zinc oxide transistor is accompanied by a densification and preferential spatial orientation of counterions at the oxide channel surface. This process occurs in three distinct steps, corresponding to ion orientations, and consequently, regimes of different electrical conductivity. The reason for this can be found in the surface charge densities on the oxide surface when different ion arrangements are present. Overall, the field-effect gating process is elucidated in terms of the interfacial ionic liquid structure, and this provides unprecedented insight into the working of a liquid gated transistor linking the nanoscopic structure to the functional properties. This knowledge will enable both new ionic liquid design as well as advanced device concepts.
Collapse
Affiliation(s)
| | | | - Sheng Bi
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST) , Wuhan 430074, China
| | - Mengyang Zhu
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST) , Wuhan 430074, China
| | - Wei Zhao
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST) , Wuhan 430074, China
| | | | | | | | | | | | | | | | | | | | - Guang Feng
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST) , Wuhan 430074, China
| | | |
Collapse
|
4
|
Tang S, Kravchenko I, Ward TZ, Zou Q, Yi J, Ma C, Chi M, Cao G, Li AP, Mandrus D, Gai Z. Dimensionality Effects in FeGe 2 Nanowires: Enhanced Anisotropic Magnetization and Anomalous Electrical Transport. Sci Rep 2017; 7:7126. [PMID: 28769040 PMCID: PMC5541131 DOI: 10.1038/s41598-017-05771-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [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: 01/20/2017] [Accepted: 05/30/2017] [Indexed: 11/09/2022] Open
Abstract
We report the synthesis of single-crystal iron germanium nanowires via chemical vapor deposition without the assistance of any catalysts. The assembly of single-crystal FeGe2 nanowires with tetragonal C16 crystal structure shows anisotropic magnetic behavior along the radial direction or the growth axial direction, with both antiferromagnetic and ferromagnetic orders. Single FeGe2 nanowire devices were fabricated using e-beam lithography. Electronic transport measurement in these devices show two resistivity anomalies near 250 K and 200 K which are likely signatures of the two spin density wave states in FeGe2.
Collapse
Affiliation(s)
- Siwei Tang
- State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083, China.,Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37996, USA.,Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Ivan Kravchenko
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - T Z Ward
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Qiang Zou
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Jieyu Yi
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37996, USA.,Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Cheng Ma
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Miaofang Chi
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Guixin Cao
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - An-Ping Li
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - David Mandrus
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37996, USA. .,Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
| | - Zheng Gai
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
| |
Collapse
|
5
|
Abstract
The optical band gap of the prototypical semiconducting oxide SnO2 is shown to be continuously controlled through single axis lattice expansion of nanometric films induced by low-energy helium implantation. While traditional epitaxy-induced strain results in Poisson driven multidirectional lattice changes shown to only allow discrete increases in bandgap, we find that a downward shift in the band gap can be linearly dictated as a function of out-of-plane lattice expansion. Our experimental observations closely match density functional theory that demonstrates that uniaxial strain provides a fundamentally different effect on the band structure than traditional epitaxy-induced multiaxes strain effects. Charge density calculations further support these findings and provide evidence that uniaxial strain can be used to drive orbital hybridization inaccessible with traditional strain engineering techniques.
Collapse
Affiliation(s)
- Andreas Herklotz
- Materials Science and Technology Division, ORNL , Bethel Valley Road, Oak Ridge, Tennessee 37831-6056, United States
| | - Stefania Florina Rus
- Renewable Energies Laboratory - Photovoltaics, National Institute for Research and Development in Electrochemistry and Condensed Matter , Timisoara 300569, Romania
| | - Thomas Zac Ward
- Materials Science and Technology Division, ORNL , Bethel Valley Road, Oak Ridge, Tennessee 37831-6056, United States
| |
Collapse
|
6
|
Liu ZQ, Li L, Gai Z, Clarkson JD, Hsu SL, Wong AT, Fan LS, Lin MW, Rouleau CM, Ward TZ, Lee HN, Sefat AS, Christen HM, Ramesh R. Full Electroresistance Modulation in a Mixed-Phase Metallic Alloy. Phys Rev Lett 2016; 116:097203. [PMID: 26991197 DOI: 10.1103/physrevlett.116.097203] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Indexed: 06/05/2023]
Abstract
We report a giant, ∼22%, electroresistance modulation for a metallic alloy above room temperature. It is achieved by a small electric field of 2 kV/cm via piezoelectric strain-mediated magnetoelectric coupling and the resulting magnetic phase transition in epitaxial FeRh/BaTiO_{3} heterostructures. This work presents detailed experimental evidence for an isothermal magnetic phase transition driven by tetragonality modulation in FeRh thin films, which is in contrast to the large volume expansion in the conventional temperature-driven magnetic phase transition in FeRh. Moreover, all the experimental results in this work illustrate FeRh as a mixed-phase model system well similar to phase-separated colossal magnetoresistance systems with phase instability therein.
Collapse
Affiliation(s)
- Z Q Liu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - L Li
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Z Gai
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J D Clarkson
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - S L Hsu
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - A T Wong
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - L S Fan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M-W Lin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - C M Rouleau
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - T Z Ward
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - H N Lee
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - A S Sefat
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - H M Christen
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - R Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| |
Collapse
|
7
|
Cao G, Singh DJ, Zhang XG, Samolyuk G, Qiao L, Parish C, Jin K, Zhang Y, Guo H, Tang S, Wang W, Yi J, Cantoni C, Siemons W, Payzant EA, Biegalski M, Ward TZ, Mandrus D, Stocks GM, Gai Z. Ferromagnetism and nonmetallic transport of thin-film α-FeSi(2): a stabilized metastable material. Phys Rev Lett 2015; 114:147202. [PMID: 25910157 DOI: 10.1103/physrevlett.114.147202] [Citation(s) in RCA: 4] [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] [Received: 09/01/2014] [Indexed: 06/04/2023]
Abstract
A metastable phase α-FeSi_{2} was epitaxially stabilized on a silicon substrate using pulsed laser deposition. Nonmetallic and ferromagnetic behaviors are tailored on α-FeSi_{2} (111) thin films, while the bulk material of α-FeSi_{2} is metallic and nonmagnetic. The transport property of the films renders two different conducting states with a strong crossover at 50 K, which is accompanied by the onset of a ferromagnetic transition as well as a substantial magnetoresistance. These experimental results are discussed in terms of the unusual electronic structure of α-FeSi_{2} obtained within density functional calculations and Boltzmann transport calculations with and without strain. Our finding sheds light on achieving ferromagnetic semiconductors through both their structure and doping tailoring, and provides an example of a tailored material with rich functionalities for both basic research and practical applications.
Collapse
Affiliation(s)
- Guixin Cao
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - D J Singh
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
| | - X-G Zhang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - German Samolyuk
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
| | - Liang Qiao
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Chad Parish
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
| | - Ke Jin
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Yanwen Zhang
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Hangwen Guo
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
| | - Siwei Tang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Wenbin Wang
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
| | - Jieyu Yi
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Claudia Cantoni
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
| | - Wolter Siemons
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
| | - E Andrew Payzant
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Michael Biegalski
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - T Z Ward
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
| | - David Mandrus
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - G M Stocks
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
| | - Zheng Gai
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| |
Collapse
|
8
|
Gai Z, Lin W, Burton JD, Fuchigami K, Snijders PC, Ward TZ, Tsymbal EY, Shen J, Jesse S, Kalinin SV, Baddorf AP. Chemically induced Jahn-Teller ordering on manganite surfaces. Nat Commun 2014; 5:4528. [PMID: 25058540 DOI: 10.1038/ncomms5528] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 06/26/2014] [Indexed: 12/27/2022] Open
Abstract
Physical and electrochemical phenomena at the surfaces of transition metal oxides and their coupling to local functionality remains one of the enigmas of condensed matter physics. Understanding the emergent physical phenomena at surfaces requires the capability to probe the local composition, map order parameter fields and establish their coupling to electronic properties. Here we demonstrate that measuring the sub-30-pm displacements of atoms from high-symmetry positions in the atomically resolved scanning tunnelling microscopy allows the physical order parameter fields to be visualized in real space on the single-atom level. Here, this local crystallographic analysis is applied to the in-situ-grown manganite surfaces. In particular, using direct bond-angle mapping we report direct observation of structural domains on manganite surfaces, and trace their origin to surface-chemistry-induced stabilization of ordered Jahn-Teller displacements. Density functional calculations provide insight into the intriguing interplay between the various degrees of freedom now resolved on the atomic level.
Collapse
Affiliation(s)
- Zheng Gai
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Wenzhi Lin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J D Burton
- Nebraska Center for Materials and Nanoscience and Department of Physics and Astronomy, University of Nebraska Lincoln, Lincoln, Nebraska 68588, USA
| | - K Fuchigami
- Research Laboratory, IHI Corporation, Yokohama, Kanagawa 235-8501, Japan
| | - P C Snijders
- 1] Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - T Z Ward
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Evgeny Y Tsymbal
- Nebraska Center for Materials and Nanoscience and Department of Physics and Astronomy, University of Nebraska Lincoln, Lincoln, Nebraska 68588, USA
| | - J Shen
- 1] Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA [2] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Stephen Jesse
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Sergei V Kalinin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Arthur P Baddorf
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| |
Collapse
|
9
|
Beekman C, Siemons W, Ward TZ, Chi M, Howe J, Biegalski MD, Balke N, Maksymovych P, Farrar AK, Romero JB, Gao P, Pan XQ, Tenne DA, Christen HM. Phase transitions, phase coexistence, and piezoelectric switching behavior in highly strained BiFeO(3) films. Adv Mater 2013; 25:5561-7. [PMID: 23847158 DOI: 10.1002/adma.201302066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Indexed: 05/12/2023]
Abstract
Highly strained BiFeO3 films transition into a true tetragonal state at 430 °C but remain polar to much higher temperatures (∼800 °C). Piezoelectric switching is only possible up to 300 °C, i.e., at temperatures for which strain stabilizes the stripe-like coexistence of multiple polymorphs.
Collapse
Affiliation(s)
- C Beekman
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Ward TZ, Gai Z, Xu XY, Guo HW, Yin LF, Shen J. Tuning the metal-insulator transition in manganite films through surface exchange coupling with magnetic nanodots. Phys Rev Lett 2011; 106:157207. [PMID: 21568612 DOI: 10.1103/physrevlett.106.157207] [Citation(s) in RCA: 6] [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: 08/19/2010] [Indexed: 05/30/2023]
Abstract
In strongly correlated electronic systems, the global transport behavior depends sensitively on spin ordering. We show that spin ordering in manganites can be controlled by depositing isolated ferromagnetic nanodots at the surface. The exchange field at the interface is tunable with nanodot density and makes it possible to overcome dimensionality and strain effects in frustrated systems to greatly increasing the metal-insulator transition and magnetoresistance. These findings indicate that electronic phase separation can be controlled by the presence of magnetic nanodots.
Collapse
Affiliation(s)
- T Z Ward
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA.
| | | | | | | | | | | |
Collapse
|
11
|
Sun D, Yin L, Sun C, Guo H, Gai Z, Zhang XG, Ward TZ, Cheng Z, Shen J. Giant magnetoresistance in organic spin valves. Phys Rev Lett 2010; 104:236602. [PMID: 20867259 DOI: 10.1103/physrevlett.104.236602] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Indexed: 05/29/2023]
Abstract
Interfacial diffusion between magnetic electrodes and organic spacer layers is a serious problem in the organic spintronics which complicates attempts to understand the spin-dependent transport mechanism and hurts the achievement of a desirably high magnetoresistance (MR). We deposit nanodots instead of atoms onto the organic layer using buffer layer assist growth. Spin valves using this method exhibit a sharper interface and a giant MR of up to ∼300%. Analysis of the current-voltage characteristics indicates that the spin-dependent carrier injection correlates with the observed MR.
Collapse
Affiliation(s)
- Dali Sun
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Ward TZ, Zhang XG, Yin LF, Zhang XQ, Liu M, Snijders PC, Jesse S, Plummer EW, Cheng ZH, Dagotto E, Shen J. Time-resolved electronic phase transitions in manganites. Phys Rev Lett 2009; 102:087201. [PMID: 19257781 DOI: 10.1103/physrevlett.102.087201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Indexed: 05/27/2023]
Abstract
The dynamics of first-order electronic phase transitions in complex transition metal oxides are not well understood but are crucial in understanding the emergent phenomena of electronic phase separation. We show that a manganite system reduced to the scale of its inherent electronic charge-ordered insulating and ferromagnetic metal phase domains allows for the direct observation of single electronic phase domain fluctuations within a critical regime of temperature and magnetic field at the metal-insulator transition.
Collapse
Affiliation(s)
- T Z Ward
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Fuchigami K, Gai Z, Ward TZ, Yin LF, Snijders PC, Plummer EW, Shen J. Tunable metallicity of the La5/8Ca3/8MnO3(001) surface by an oxygen overlayer. Phys Rev Lett 2009; 102:066104. [PMID: 19257611 DOI: 10.1103/physrevlett.102.066104] [Citation(s) in RCA: 8] [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: 11/10/2008] [Indexed: 05/27/2023]
Abstract
We studied the surface structure of La_{5/8}Ca_{3/8}MnO_{3}(001) thin films using in situ scanning tunneling microscopy (STM). Atomically resolved STM images reveal that a (sqrt[2]xsqrt[2])R45;{ degrees } reconstructed surface and a (1x1) surface can be converted back and forth through adsorption and desorption of oxygen at the surface. The electrical properties of the surfaces are investigated by scanning tunneling spectroscopy. I-V curves clearly show that the presence of an oxygen overlayer renders the surface insulating while the (1x1) surface without the oxygen overlayer is metallic.
Collapse
Affiliation(s)
- K Fuchigami
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | | | | | | | | | | | | |
Collapse
|
14
|
Ward TZ, Liang S, Fuchigami K, Yin LF, Dagotto E, Plummer EW, Shen J. Reemergent metal-insulator transitions in manganites exposed with spatial confinement. Phys Rev Lett 2008; 100:247204. [PMID: 18643624 DOI: 10.1103/physrevlett.100.247204] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Indexed: 05/26/2023]
Abstract
The metal-insulator transition is characterized as a single peak in the temperature-dependent resistivity measurements; exceptions to this have never been seen in any single crystal material system. We show that by reducing a single crystal manganite thin film to a wire with a width comparable to the mesoscopic phase-separated domains inherent in the material, a second and robust metal-insulator transition peak appears in the resistivity versus temperature measurement. This new observation suggests that spatial confinement is a promising route for the discovery of emergent physical phenomena in complex oxides.
Collapse
Affiliation(s)
- T Z Ward
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | | | | | | | | | | | | |
Collapse
|
15
|
Zhai HY, Ma JX, Gillaspie DT, Zhang XG, Ward TZ, Plummer EW, Shen J. Giant discrete steps in metal-insulator transition in perovskite manganite wires. Phys Rev Lett 2006; 97:167201. [PMID: 17155428 DOI: 10.1103/physrevlett.97.167201] [Citation(s) in RCA: 9] [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: 08/01/2006] [Indexed: 05/12/2023]
Abstract
Optical lithography is used to fabricate LPCMO wires starting from a single (La(5/8-0.3)Pr(0.3))Ca3/8MnO3 (LPCMO) film epitaxially grown on a LaAlO3(100) substrate. As the width of the wires is decreased, the resistivity of the LPCMO wires exhibits giant and ultrasharp steps upon varying temperature and magnetic field in the vicinity of the metal-insulator transition. The origin of the ultrasharp transitions is attributed to the effect of spatial confinement on the percolative transport in manganites.
Collapse
Affiliation(s)
- Hong-Ying Zhai
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | | | | | | | | | | | | |
Collapse
|