1
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Du EW, Gong SJ, Tang X, Chu J, Rappe AM, Gong C. Ferroelectric Switching of Pure Spin Polarization in Two-Dimensional Electron Gas. NANO LETTERS 2020; 20:7230-7236. [PMID: 32786931 DOI: 10.1021/acs.nanolett.0c02584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Two-dimensional electron gas (2DEG) created at compound interfaces can exhibit a broad range of exotic physical phenomena, including quantum Hall phase, emergent ferromagnetism, and superconductivity. Although electron spin plays key roles in these phenomena, the fundamental understanding and application prospects of such emergent interfacial states have been largely impeded by the lack of purely spin-polarized 2DEG. In this work, by first-principles calculations of the multiferroic superlattice GeTe/MnTe, we find the ferroelectric polarization of GeTe is concurrent with the half-metallic 2DEG at interfaces. Remarkably, the pure spin polarization of the 2DEG can be created and annihilated by polarizing and depolarizing the ferroelectrics and can be switched (between pure spin-up and pure spin-down) by flipping the ferroelectric polarization. Given the electric-field amplification effect of ferroelectric electronics, we envision multiferroic superlattices could open up new opportunities for low-power, high-efficiency spintronic devices such as spin field-effect transistors.
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Affiliation(s)
- Er-Wei Du
- Key Laboratory of Polar Materials and Devices (MOE), Department of Optoelectronics, East China Normal University, Shanghai 200241, China
| | - Shi-Jing Gong
- Key Laboratory of Polar Materials and Devices (MOE), Department of Optoelectronics, East China Normal University, Shanghai 200241, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Shanghai Institute of Intelligent Electronics & Systems, Fudan University, Shanghai 200433, China
| | - Xiaodong Tang
- Key Laboratory of Polar Materials and Devices (MOE), Department of Optoelectronics, East China Normal University, Shanghai 200241, China
| | - Junhao Chu
- Department of Materials Science, Fudan University, Shanghai 200433, China
| | - Andrew M Rappe
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Cheng Gong
- Department of Electrical and Computer Engineering and Quantum Technology Center, University of Maryland, College Park, Maryland 20742, United States
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2
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Kriener M, Sakano M, Kamitani M, Bahramy MS, Yukawa R, Horiba K, Kumigashira H, Ishizaka K, Tokura Y, Taguchi Y. Evolution of Electronic States and Emergence of Superconductivity in the Polar Semiconductor GeTe by Doping Valence-Skipping Indium. PHYSICAL REVIEW LETTERS 2020; 124:047002. [PMID: 32058775 DOI: 10.1103/physrevlett.124.047002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Indexed: 06/10/2023]
Abstract
GeTe is a chemically simple IV-VI semiconductor which bears a rich plethora of different physical properties induced by doping and external stimuli. Here, we report a superconductor-semiconductor-superconductor transition controlled by finely-tuned In doping. Our results reveal the existence of a critical doping concentration x_{c}=0.12 in Ge_{1-x}In_{x}Te, where various properties, including structure, resistivity, charge carrier type, and the density of states, take either an extremum or change their character. At the same time, we find indications of a change in the In-valence state from In^{3+} to In^{1+} with increasing x by core-level photoemission spectroscopy, suggesting that this system is a new promising playground to probe valence fluctuations and their possible impact on structural, electronic, and thermodynamic properties of their host.
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Affiliation(s)
- M Kriener
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - M Sakano
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
| | - M Kamitani
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - M S Bahramy
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
| | - R Yukawa
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
| | - K Horiba
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
| | - H Kumigashira
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai 980-8577, Japan
| | - K Ishizaka
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
| | - Y Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
- Tokyo College, University of Tokyo, Tokyo 113-8656, Japan
| | - Y Taguchi
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
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3
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Abstract
Ferroelectric materials are used in actuators or sensors because of their non-volatile macroscopic electric polarization. GeTe is the simplest known diatomic ferroelectric endowed with exceedingly complex physics related to its crystalline, amorphous, thermoelectric, and—fairly recently discovered—topological properties, making the material potentially interesting for spintronics applications. Typically, ferroelectric materials possess random oriented domains that need poling to achieve macroscopic polarization. By using X-ray absorption fine structure spectroscopy complemented with anomalous diffraction and piezo-response force microscopy, we investigated the bulk ferroelectric structure of GeTe crystals and thin films. Both feature multi-domain structures in the form of oblique domains for films and domain colonies inside crystals. Despite these multi-domain structures which are expected to randomize the polarization direction, our experimental results show that at room temperature there is a preferential ferroelectric order remarkably consistent with theoretical predictions from ideal GeTe crystals. This robust self-poled state has high piezoelectricity and additional poling reveals persistent memory effects.
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4
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Yoshimi R, Yasuda K, Tsukazaki A, Takahashi KS, Kawasaki M, Tokura Y. Current-driven magnetization switching in ferromagnetic bulk Rashba semiconductor (Ge,Mn)Te. SCIENCE ADVANCES 2018; 4:eaat9989. [PMID: 30539144 PMCID: PMC6286171 DOI: 10.1126/sciadv.aat9989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 11/06/2018] [Indexed: 06/09/2023]
Abstract
Multiferroic materials with both ferroelectric and ferromagnetic orders provide a promising arena for the electrical manipulation of magnetization through the mutual correlation between those ferroic orders. Such a concept of multiferroics may expand to semiconductor with both broken symmetries of spatial inversion and time reversal, that is, polar ferromagnetic semiconductors. Here, we report the observation of current-driven magnetization switching in one such example, (Ge,Mn)Te thin films. The ferromagnetism caused by Mn doping opens an exchange gap in original massless Dirac band of the polar semiconductor GeTe with Rashba-type spin-split bands. The anomalous Hall conductivity is enhanced with increasing hole carrier density, indicating that the contribution of the Berry phase is maximized as the Fermi level approaches the exchange gap. By means of pulse-current injection, the electrical switching of the magnetization is observed in the (Ge,Mn)Te thin films as thick as 200 nm, pointing to the Rashba-Edelstein effect of bulk origin. The efficiency of this effect strongly depends on the Fermi-level position owing to the efficient spin accumulation at around the gap. The magnetic bulk Rashba system will be a promising platform for exploring the functional correlations among electric polarization, magnetization, and current.
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Affiliation(s)
- R. Yoshimi
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - K. Yasuda
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
| | - A. Tsukazaki
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - K. S. Takahashi
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- PRESTO, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0075, Japan
| | - M. Kawasaki
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
| | - Y. Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
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5
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Physical properties of cubic BaGeO 3 perovskite at various pressure using first-principle calculations for energy renewable devices. J Mol Graph Model 2018; 84:152-159. [PMID: 29975866 DOI: 10.1016/j.jmgm.2018.06.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 06/27/2018] [Accepted: 06/27/2018] [Indexed: 11/21/2022]
Abstract
The electronic, optical and thermoelectric analyses of BaGeO3 perovskite have been done by using density functional theory (DFT) based Trans and Blaha modified Becke and Johnson (TB-mBJ) approach. The applied pressure (up to 30 GPa) has been found tailoring the band gap from indirect to direct bandgap (at 20 GPa), within the visible region, revealing renewable energy applications of the studied perovskite. The applied pressure improves mechanical stability by increasing ductility. Furthermore, optical properties are illustrated by computing dielectric constants, refraction, absorption, optical conductivity and optical loss factor for suggesting optoelectronic applications. The maximum peaks shifting to higher energy, due to increasing pressure indicate a blue shift. Finally, the calculated thermal and electrical conductivities, See-beck coefficient, power factor, Hall coefficient, specific heat capacity, susceptibility and electron densities are also elaborated for thermoelectric applications by using BoltzTraP code.
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6
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Mantovan R, Fallica R, Mokhles Gerami A, Mølholt TE, Wiemer C, Longo M, Gunnlaugsson HP, Johnston K, Masenda H, Naidoo D, Ncube M, Bharuth-Ram K, Fanciulli M, Gislason HP, Langouche G, Ólafsson S, Weyer G. Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films. Sci Rep 2017; 7:8234. [PMID: 28811632 PMCID: PMC5558007 DOI: 10.1038/s41598-017-08275-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 07/10/2017] [Indexed: 11/25/2022] Open
Abstract
The underlying mechanism driving the structural amorphous-to-crystalline transition in Group VI chalcogenides is still a matter of debate even in the simplest GeTe system. We exploit the extreme sensitivity of 57Fe emission Mössbauer spectroscopy, following dilute implantation of 57Mn (T½ = 1.5 min) at ISOLDE/CERN, to study the electronic charge distribution in the immediate vicinity of the 57Fe probe substituting Ge (FeGe), and to interrogate the local environment of FeGe over the amorphous-crystalline phase transition in GeTe thin films. Our results show that the local structure of as-sputtered amorphous GeTe is a combination of tetrahedral and defect-octahedral sites. The main effect of the crystallization is the conversion from tetrahedral to defect-free octahedral sites. We discover that only the tetrahedral fraction in amorphous GeTe participates to the change of the FeGe-Te chemical bonds, with a net electronic charge density transfer of ~ 1.6 e/a0 between FeGe and neighboring Te atoms. This charge transfer accounts for a lowering of the covalent character during crystallization. The results are corroborated by theoretical calculations within the framework of density functional theory. The observed atomic-scale chemical-structural changes are directly connected to the macroscopic phase transition and resistivity switch of GeTe thin films.
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Affiliation(s)
- R Mantovan
- Laboratorio MDM, IMM-CNR, Via Olivetti 2, 20864, Agrate Brianza (MB), Italy.
| | - R Fallica
- Laboratorio MDM, IMM-CNR, Via Olivetti 2, 20864, Agrate Brianza (MB), Italy.,Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
| | - A Mokhles Gerami
- Physics Department, ISOLDE/CERN, Geneva 23, Switzerland.,Dept. of Physics, K. N. Toosi University of Technology, P.O. Box 15875-4416, Tehran, Iran
| | - T E Mølholt
- Physics Department, ISOLDE/CERN, Geneva 23, Switzerland
| | - C Wiemer
- Laboratorio MDM, IMM-CNR, Via Olivetti 2, 20864, Agrate Brianza (MB), Italy
| | - M Longo
- Laboratorio MDM, IMM-CNR, Via Olivetti 2, 20864, Agrate Brianza (MB), Italy.
| | - H P Gunnlaugsson
- Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavík, Iceland
| | - K Johnston
- Physics Department, ISOLDE/CERN, Geneva 23, Switzerland
| | - H Masenda
- School of Physics, University of the Witwatersrand, Johannesburg, 2050, South Africa
| | - D Naidoo
- School of Physics, University of the Witwatersrand, Johannesburg, 2050, South Africa
| | - M Ncube
- School of Physics, University of the Witwatersrand, Johannesburg, 2050, South Africa
| | - K Bharuth-Ram
- Durban University of Technology, Durban, 4000, South Africa.,School of Chemistry and Physics, University of KwaZulu-Natal, Durban, 4000, South Africa
| | - M Fanciulli
- Laboratorio MDM, IMM-CNR, Via Olivetti 2, 20864, Agrate Brianza (MB), Italy.,Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Milano, Italy
| | - H P Gislason
- Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavík, Iceland
| | - G Langouche
- KU Leuven, Instituut voor Kern-en Stralings Fysika, B-3001, Leuven, Belgium
| | - S Ólafsson
- Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavík, Iceland
| | - G Weyer
- Department of Physics and Astronomy, Aarhus University, Aarhus C, Denmark
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7
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Inverting polar domains via electrical pulsing in metallic germanium telluride. Nat Commun 2017; 8:15033. [PMID: 28401949 PMCID: PMC5394341 DOI: 10.1038/ncomms15033] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 02/22/2017] [Indexed: 01/29/2023] Open
Abstract
Germanium telluride (GeTe) is both polar and metallic, an unusual combination of properties in any material system. The large concentration of free-carriers in GeTe precludes the coupling of external electric field with internal polarization, rendering it ineffective for conventional ferroelectric applications and polarization switching. Here we investigate alternate ways of coupling the polar domains in GeTe to external electrical stimuli through optical second harmonic generation polarimetry and in situ TEM electrical testing on single-crystalline GeTe nanowires. We show that anti-phase boundaries, created from current pulses (heat shocks), invert the polarization of selective domains resulting in reorganization of certain 71o domain boundaries into 109o boundaries. These boundaries subsequently interact and evolve with the partial dislocations, which migrate from domain to domain with the carrier-wind force (electrical current). This work suggests that current pulses and carrier-wind force could be external stimuli for domain engineering in ferroelectrics with significant current leakage. Polar metals such as GeTe could store information using electric domains but the high conductivity screens electric fields, preventing the use of usual domain control techniques. Here, the authors demonstrate that polar domains in GeTe can be manipulated using electrically generated heat shocks.
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8
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Boschker JE, Wang R, Calarco R. GeTe: a simple compound blessed with a plethora of properties. CrystEngComm 2017. [DOI: 10.1039/c7ce01040k] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A selection from the wide range of functional properties present in the binary compound, GeTe, are reviewed is this paper.
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Affiliation(s)
- Jos E. Boschker
- Paul-Drude-Institut für Festkörperelektronik
- 10117 Berlin
- Germany
| | - Ruining Wang
- Paul-Drude-Institut für Festkörperelektronik
- 10117 Berlin
- Germany
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9
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Krempaský J, Muff S, Bisti F, Fanciulli M, Volfová H, Weber AP, Pilet N, Warnicke P, Ebert H, Braun J, Bertran F, Volobuev VV, Minár J, Springholz G, Dil JH, Strocov VN. Entanglement and manipulation of the magnetic and spin-orbit order in multiferroic Rashba semiconductors. Nat Commun 2016; 7:13071. [PMID: 27767052 PMCID: PMC5078730 DOI: 10.1038/ncomms13071] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 08/31/2016] [Indexed: 11/17/2022] Open
Abstract
Entanglement of the spin–orbit and magnetic order in multiferroic materials bears a strong potential for engineering novel electronic and spintronic devices. Here, we explore the electron and spin structure of ferroelectric α-GeTe thin films doped with ferromagnetic Mn impurities to achieve its multiferroic functionality. We use bulk-sensitive soft-X-ray angle-resolved photoemission spectroscopy (SX-ARPES) to follow hybridization of the GeTe valence band with the Mn dopants. We observe a gradual opening of the Zeeman gap in the bulk Rashba bands around the Dirac point with increase of the Mn concentration, indicative of the ferromagnetic order, at persistent Rashba splitting. Furthermore, subtle details regarding the spin–orbit and magnetic order entanglement are deduced from spin-resolved ARPES measurements. We identify antiparallel orientation of the ferroelectric and ferromagnetic polarization, and altering of the Rashba-type spin helicity by magnetic switching. Our experimental results are supported by first-principles calculations of the electron and spin structure. In α-GeTe, ferroelectric polarization acts to break inversion symmetry of the lattice and induce a strong Rashba-type spin splitting of the electronic band structure. Here, the authors study how this effect competes with Zeeman splitting due to ferromagnetic exchange coupling in Mn-doped GeTe.
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Affiliation(s)
- J Krempaský
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - S Muff
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.,Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - F Bisti
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Fanciulli
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.,Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - H Volfová
- Department of Chemistry, Ludwig Maximillian University, 81377 Munich, Germany
| | - A P Weber
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.,Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - N Pilet
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - P Warnicke
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - H Ebert
- Department of Chemistry, Ludwig Maximillian University, 81377 Munich, Germany
| | - J Braun
- Department of Chemistry, Ludwig Maximillian University, 81377 Munich, Germany
| | - F Bertran
- SOLEIL Synchrotron, L'Orme des Merisiers, F-91192 Gif-sur-Yvette, France
| | - V V Volobuev
- National Technical University, Kharkiv Polytechnic Institute, Frunze Str. 21, 61002 Kharkiv, Ukraine.,Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria
| | - J Minár
- Department of Chemistry, Ludwig Maximillian University, 81377 Munich, Germany.,New Technologies-Research Center University of West Bohemia, Plzeň, Czech Republic
| | - G Springholz
- Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria
| | - J H Dil
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.,Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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10
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Kriegner D, Furthmüller J, Kirchschlager R, Endres J, Horak L, Cejpek P, Reichlova H, Marti X, Primetzhofer D, Ney A, Bauer G, Bechstedt F, Holy V, Springholz G. Ferroelectric phase transition in multiferroic Ge 1-x Mn x Te driven by local lattice distortions. PHYSICAL REVIEW. B 2016; 94:054112. [PMID: 28459114 PMCID: PMC5404721 DOI: 10.1103/physrevb.94.054112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The evolution of local ferroelectric lattice distortions in multiferroic Ge1-x Mn x Te is studied by x-ray diffraction, x-ray absorption spectroscopy and density functional theory. We show that the anion/cation displacements smoothly decrease with increasing Mn content, thereby reducing the ferroelectric transition from 700 to 100 K at x = 0.5, where the ferromagnetic Curie temperature reaches its maximum. First principles calculations explain this quenching by different local bond contributions of the Mn 3d shell compared to the Ge 4s shell in excellent quantitative agreement with the experiments.
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Affiliation(s)
- Dominik Kriegner
- Department of Condensed Matter Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2, Czech Republic
| | - Jürgen Furthmüller
- Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena, Germany
| | - Raimund Kirchschlager
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria
| | - Jan Endres
- Department of Condensed Matter Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2, Czech Republic
| | - Lukas Horak
- Department of Condensed Matter Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2, Czech Republic
| | - Petr Cejpek
- Department of Condensed Matter Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2, Czech Republic
| | - Helena Reichlova
- Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - Xavier Marti
- Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - Daniel Primetzhofer
- Ion Physics Department, The Ångström Laboratory, Uppsala University, P.O. Box 534, SE-75121, Sweden
| | - Andreas Ney
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria
| | - Günther Bauer
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria
| | - Friedhelm Bechstedt
- Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena, Germany
| | - Vaclav Holy
- Department of Condensed Matter Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2, Czech Republic
| | - Gunther Springholz
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria
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11
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Heat-Treatment-Induced Switching of Magnetic States in the Doped Polar Semiconductor Ge1-xMnxTe. Sci Rep 2016; 6:25748. [PMID: 27160657 PMCID: PMC4861972 DOI: 10.1038/srep25748] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 04/22/2016] [Indexed: 11/09/2022] Open
Abstract
Cross-control of a material property - manipulation of a physical quantity (e.g., magnetisation) by a nonconjugate field (e.g., electrical field) - is a challenge in fundamental science and also important for technological device applications. It has been demonstrated that magnetic properties can be controlled by electrical and optical stimuli in various magnets. Here we find that heat-treatment allows the control over two competing magnetic phases in the Mn-doped polar semiconductor GeTe. The onset temperatures Tc of ferromagnetism vary at low Mn concentrations by a factor of five to six with a maximum Tc ≈ 180 K, depending on the selected phase. Analyses in terms of synchrotron x-ray diffraction and energy dispersive x-ray spectroscopy indicate a possible segregation of the Mn ions, which is responsible for the high-Tc phase. More importantly, we demonstrate that the two states can be switched back and forth repeatedly from either phase by changing the heat-treatment of a sample, thereby confirming magnetic phase-change-memory functionality.
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12
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Łusakowski A, Bogusławski P, Story T. DFT calculations of magnetic anisotropy energy of Ge(1-x)Mn(x)Te ferromagnetic semiconductor. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:226002. [PMID: 25988352 DOI: 10.1088/0953-8984/27/22/226002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Density functional theory (DFT) calculations of the energy of magnetic anisotropy for diluted ferromagnetic semiconductor Ge(1-x)Mn(x)Te were performed using OpenMX package with fully relativistic pseudopotentials. The influence of hole concentration and magnetic ion neighbourhood on magnetic anisotropy energy is presented. Analysis of microscopic mechanism of magnetic anisotropy is provided, in particular the role of spin-orbit coupling, spin polarization and spatial changes of electron density are discussed. The calculations are in accordance with the experimental observation of perpendicular magnetic anisotropy in rhombohedral Ge(1-x)Mn(x)Te (1 1 1) thin layers.
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Affiliation(s)
- A Łusakowski
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
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