1
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Huang SM, Wang PC, Chen PC. The Lattice Distortion-Induced Ferromagnetism in the Chemical-Bonded MoSe 2/WSe 2 at Room Temperature. NANOSCALE RESEARCH LETTERS 2022; 17:55. [PMID: 35622164 PMCID: PMC9142725 DOI: 10.1186/s11671-022-03692-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/13/2022] [Indexed: 06/15/2023]
Abstract
Ferromagnetism to non-ferromagnetism transition is detected in a chemically bonded MoSe[Formula: see text]/WSe[Formula: see text] powder with different thermal annealing temperatures. All samples exhibit ferromagnetism and Raman redshift, except for the 1100 °C thermally annealed sample in which the MoSe[Formula: see text] and WSe[Formula: see text] are thermally dissociated and geometrically separated. The element analysis reveals no significant element ratio difference and detectable magnetic elements in all samples. These results support that, in contrast to the widely reported structure defect or transition element dopant, the observed ferromagnetism originates from the structure distortion due to the chemical bonding at the interface between MoSe[Formula: see text] and WSe[Formula: see text].
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Affiliation(s)
- Shiu-Ming Huang
- Department of Physics, National Sun Yat-Sen University, 80424, Kaohsiung, Taiwan.
| | - Pin-Cing Wang
- Department of Physics, National Sun Yat-Sen University, 80424, Kaohsiung, Taiwan
| | - Pin-Cyuan Chen
- Department of Physics, National Sun Yat-Sen University, 80424, Kaohsiung, Taiwan
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2
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Liu J, Hesjedal T. Magnetic Topological Insulator Heterostructures: A Review. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021:e2102427. [PMID: 34665482 DOI: 10.1002/adma.202102427] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/05/2021] [Indexed: 06/13/2023]
Abstract
Topological insulators (TIs) provide intriguing prospects for the future of spintronics due to their large spin-orbit coupling and dissipationless, counter-propagating conduction channels in the surface state. The combination of topological properties and magnetic order can lead to new quantum states including the quantum anomalous Hall effect that was first experimentally realized in Cr-doped (Bi,Sb)2 Te3 films. Since magnetic doping can introduce detrimental effects, requiring very low operational temperatures, alternative approaches are explored. Proximity coupling to magnetically ordered systems is an obvious option, with the prospect to raise the temperature for observing the various quantum effects. Here, an overview of proximity coupling and interfacial effects in TI heterostructures is presented, which provides a versatile materials platform for tuning the magnetic and topological properties of these exciting materials. An introduction is first given to the heterostructure growth by molecular beam epitaxy and suitable structural, electronic, and magnetic characterization techniques. Going beyond transition-metal-doped and undoped TI heterostructures, examples of heterostructures are discussed, including rare-earth-doped TIs, magnetic insulators, and antiferromagnets, which lead to exotic phenomena such as skyrmions and exchange bias. Finally, an outlook on novel heterostructures such as intrinsic magnetic TIs and systems including 2D materials is given.
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Affiliation(s)
- Jieyi Liu
- Clarendon Laboratory, Department of Physics University of Oxford, Parks Road, Oxford, OX1 3PU, UK
| | - Thorsten Hesjedal
- Clarendon Laboratory, Department of Physics University of Oxford, Parks Road, Oxford, OX1 3PU, UK
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3
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Zhang L, Helm T, Lin H, Fan F, Le C, Sun Y, Markou A, Felser C. Quantum Oscillations in Ferromagnetic (Sb, V) 2 Te 3 Topological Insulator Thin Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2102107. [PMID: 34463975 DOI: 10.1002/adma.202102107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/14/2021] [Indexed: 06/13/2023]
Abstract
An effective way of manipulating 2D surface states in magnetic topological insulators may open a new route for quantum technologies based on the quantum anomalous Hall effect. The doping-dependent evolution of the electronic band structure in the topological insulator Sb2- x Vx Te3 (0 ≤ x ≤ 0.102) thin films is studied by means of electrical transport. Sb2- x Vx Te3 thin films were prepared by molecular beam epitaxy, and Shubnikov-de Hass (SdH) oscillations are observed in both the longitudinal and transverse transport channels. Doping with the 3d element, vanadium, induces long-range ferromagnetic order with enhanced SdH oscillation amplitudes. The doping effect is systematically studied in various films depending on thickness and bottom gate voltage. The angle-dependence of the SdH oscillations reveals their 2D nature, linking them to topological surface states as their origin. Furthermore, it is shown that vanadium doping can efficiently modify the band structure. The tunability by doping and the coexistence of the surface states with ferromagnetism render Sb2- x Vx Te3 thin films a promising platform for energy band engineering. In this way, topological quantum states may be manipulated to crossover from quantum Hall effect to quantum anomalous Hall effect, which opens an alternative route for the design of quantum electronics and spintronics.
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Affiliation(s)
- Liguo Zhang
- Max-Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Toni Helm
- Dresden High Magnetic Field Laboratory (HLD), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Haicheng Lin
- Max-Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Fengren Fan
- Max-Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Congcong Le
- Max-Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Yan Sun
- Max-Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Anastasios Markou
- Max-Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Claudia Felser
- Max-Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
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4
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Huang Y, Bai G, Zhao Y, Liu Y, Xu S, Hao J. Lanthanide-Doped Topological Nanosheets with Enhanced Near-Infrared Photothermal Performance for Energy Conversion. ACS APPLIED MATERIALS & INTERFACES 2021; 13:43094-43103. [PMID: 34460241 DOI: 10.1021/acsami.1c12562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two-dimensional inorganic semiconductor materials have aroused tremendous research interest and found their potential in resolving the present urgent global issues, such as cancer therapy and fresh water shortage. Particularly, the near-infrared (NIR) photothermal conversion efficiency is a significant parameter in photothermal therapy. However, lack of an effective improvement strategy and their relatively low NIR phothermal conversion efficiency would restrict their wide and further application. Here, this work reports that enhanced NIR photothermal conversion is achieved in topological Bi2Se3 nanosheets by introducing a lanthanide dopant. Specifically, lanthanide Pr-doped Bi2Se3 nanosheets possess a photothermal conversion efficiency of 49.5%, which is higher than those of undoped Bi2Se3 nanosheets (31.0%) and numerous reported photothermal materials. The electronic structure of Pr-doped Bi2Se3 nanosheets was also analyzed by first-principles simulation. Furthermore, an interfacial evaporation system based on the developed nanosheets has been established, demonstrating a superior solar-thermal conversion efficiency of 91.5% and a water evaporation rate of 1.669 kg m-2 h-1 under 1 sun irradiation. The present work would provide new insights for the increase in the efficiency of photothermal materials.
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Affiliation(s)
- Youqiang Huang
- College of Materials and Chemistry, China Jiliang University, Hangzhou 310018, People's Republic of China
- Key Laboratory of Rare Earth Optoelectronic Materials and Devices of Zhejiang Province, China Jiliang University, Hangzhou 310018, People's Republic of China
| | - Gongxun Bai
- Key Laboratory of Rare Earth Optoelectronic Materials and Devices of Zhejiang Province, China Jiliang University, Hangzhou 310018, People's Republic of China
| | - Yingjie Zhao
- College of Materials and Chemistry, China Jiliang University, Hangzhou 310018, People's Republic of China
- Key Laboratory of Rare Earth Optoelectronic Materials and Devices of Zhejiang Province, China Jiliang University, Hangzhou 310018, People's Republic of China
| | - Yuan Liu
- Key Laboratory of Rare Earth Optoelectronic Materials and Devices of Zhejiang Province, China Jiliang University, Hangzhou 310018, People's Republic of China
| | - Shiqing Xu
- Key Laboratory of Rare Earth Optoelectronic Materials and Devices of Zhejiang Province, China Jiliang University, Hangzhou 310018, People's Republic of China
| | - Jianhua Hao
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong 999077, People's Republic of China
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5
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Kolincio KK, Roman M, Klimczuk T. Enhanced Mobility and Large Linear Nonsaturating Magnetoresistance in the Magnetically Ordered States of TmNiC_{2}. PHYSICAL REVIEW LETTERS 2020; 125:176601. [PMID: 33156671 DOI: 10.1103/physrevlett.125.176601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 09/02/2020] [Accepted: 09/11/2020] [Indexed: 06/11/2023]
Abstract
We have studied the magnetic, magnetotransport, and galvanomagnetic properties of TmNiC_{2}. We find that the antiferromagnetic and field induced metamagnetic and ferromagnetic orderings do not suppress the charge density wave. The persistence of Fermi surface pockets, open as a result of imperfect nesting accompanying the Peierls transition, results in an electronic carriers mobility of the order of 4×10^{3} cm^{2} V^{-1} s^{-1} in ferromagnetic state, without any signatures for a significant deterioration of nesting properties. This is independently evidenced by high, nonsaturating linear magnetoresistance reaching 440% at T=2 K and an analysis of the Hall conductivity. We thus demonstrate that, the coexistence of charge density wave and magnetism provides an alternative route to maintain high electronic mobility in the magnetically ordered state.
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Affiliation(s)
- Kamil K Kolincio
- Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
| | - Marta Roman
- Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
| | - Tomasz Klimczuk
- Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
- Advanced Materials Centre, Gdansk University of Technology, ul. Narutowicza 11/12, 80-233 Gdansk, Poland
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6
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Fei F, Zhang S, Zhang M, Shah SA, Song F, Wang X, Wang B. The Material Efforts for Quantized Hall Devices Based on Topological Insulators. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1904593. [PMID: 31840308 DOI: 10.1002/adma.201904593] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/09/2019] [Indexed: 06/10/2023]
Abstract
A topological insulator (TI) is a kind of novel material hosting a topological band structure and plenty of exotic topological quantum effects. Achieving quantized electrical transport, including the quantum Hall effect (QHE) and the quantum anomalous Hall effect (QAHE), is an important aspect of realizing quantum devices based on TI materials. Intense efforts are made in this field, in which the most essential research is based on the optimization of realistic TI materials. Herein, the TI material development process is reviewed, focusing on the realization of quantized transport. Especially, for QHE, the strategies to increase the surface transport ratio and decrease the threshold magnetic field of QHE are examined. For QAHE, the evolution history of magnetic TIs is introduced, and the recently discovered magnetic TI candidates with intrinsic magnetizations are discussed in detail. Moreover, future research perspectives on these novel topological quantum effects are also evaluated.
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Affiliation(s)
- Fucong Fei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Shuai Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Minhao Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Syed Adil Shah
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Xuefeng Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
| | - Baigeng Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
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7
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Signature of topological states in antiferromagnetic Sm-substituted Bi 2Te 3. Sci Rep 2020; 10:9615. [PMID: 32541880 PMCID: PMC7296006 DOI: 10.1038/s41598-020-66521-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Accepted: 05/12/2020] [Indexed: 12/03/2022] Open
Abstract
An antiferromagnetic topological insulator has been predicted to be preserved by breaking both time-reversal symmetry and primitive lattice translational symmetry. However, the topological surface state has often been observed to disappear in an antiferromagnetic phase because the doped magnetic impurity acts as an extrinsic defect. In this study, we report the experimental signature of topological surface states coexisting with antiferromagnetic order in Sm-doped Bi2Te3. We fabricate single crystals of SmxBi2−xTe3 with x = 0.004, 0.010, and 0.025, where the Curie-Weiss law is satisfied at low temperatures but is violated at high temperatures due to the influence of the high energy states of J multiplets of Sm. For x = 0.025, e xotic physical properties are observed, such as the antiferromagnetic phase with the Néel temperature TN = 3.3 K, multi-band Hall effect with two conduction channel, and anisotropic Shubnikov-de Haas oscillations. In the antiferromagnetic phase, we detect the signature of nontrivial topological surface states with surface electron density ns = 7.9 × 1011 cm−2 and its high mobility μs = 2,200 cm2/Vs, compared to nb = 2.0 × 1019 cm−3 and μb = 2.3 cm2/Vs for bulk electrons. These observations suggest that SmxBi2−xTe3 is a candidate creating the new stage for the potential application of topological antiferromagnetic spintronics.
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8
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Tan H, Wang C, Hu W, Duan H, Guo P, Li N, Li G, Cai L, Sun Z, Hu F, Yan W. Reversible Tuning of the Ferromagnetic Behavior in Mn-Doped MoS 2 Nanosheets via Interface Charge Transfer. ACS APPLIED MATERIALS & INTERFACES 2018; 10:31648-31654. [PMID: 30156104 DOI: 10.1021/acsami.8b11623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Reversible manipulation of the magnetic behavior of two-dimensional van der Waals crystals is crucial for expanding their applications in spin-based information-processing technologies. However, to date, most experimental approaches to tune the magnetic properties are single way and have very limited practical applications. Here, we report an interface charge-transfer method for obtaining a reversible and air-stable magnetic response at room temperature in Mn-doped MoS2 nanosheets. By adsorption of benzyl viologen (BV) molecules as the charge donor, the saturation magnetization of Mn-doped MoS2 nanosheets is enhanced by a magnitude of 60%, and the magnetization can be restored to the original value when the adsorbed BV molecules are removed. This cycle can be repeated many times on the same sample without detectable degradation. Experimental characterizations and first-principles calculations suggest that the enhanced magnetization can be attributed to the increase of Mn magnetic moment because of the enriched electrons transferred from BV molecules. This work shows that interface charge transfer may open up a new pathway for reversibly tuning the exchange interactions in two-dimensional nanostructures.
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Affiliation(s)
- Hao Tan
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Chao Wang
- Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology , Chinese Academy of Sciences , Hefei 230031 , Anhui , P. R. China
| | - Wei Hu
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Hengli Duan
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Peng Guo
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Na Li
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Guinan Li
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Liang Cai
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Zhihu Sun
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Fengchun Hu
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Wensheng Yan
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
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9
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Fu D, Pan X, Bai Z, Fei F, Umana-Membreno GA, Song H, Wang X, Wang B, Song F. Tuning the electrical transport of type II Weyl semimetal WTe 2 nanodevices by Mo doping. NANOTECHNOLOGY 2018; 29:135705. [PMID: 29432212 DOI: 10.1088/1361-6528/aaa811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We fabricated nanodevices from MoxW1-xTe2 (x = 0, 0.07, 0.35), and conducted a systematic comparative study of their electrical transport. Magnetoresistance measurements show that Mo doping can significantly suppress mobility and magnetoresistance. The results for the analysis of the two band model show that doping with Mo does not break the carrier balance. Through analysis of Shubnikov-de Haas oscillations, we found that Mo doping also has a strong suppressive effect on the quantum oscillation of the sample, and the higher the ratio of Mo, the fewer pockets were observed in our experiments. Furthermore, the effective mass of electron and hole increases gradually with increasing Mo ratio, while the corresponding quantum mobility decreases rapidly.
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Affiliation(s)
- Dongzhi Fu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, Nanjing, 210093, People's Republic of China
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10
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Tuning the electrical transport of type II Weyl semimetal WTe 2 nanodevices by Ga+ ion implantation. Sci Rep 2017; 7:12688. [PMID: 28978938 PMCID: PMC5627286 DOI: 10.1038/s41598-017-12865-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 09/14/2017] [Indexed: 11/08/2022] Open
Abstract
Here we introduce lattice defects in WTe2 by Ga+ implantation (GI), and study the effects of defects on the transport properties and electronic structures of the samples. Theoretical calculation shows that Te Frenkel defects is the dominant defect type, and Raman characterization results agree with this. Electrical transport measurements show that, after GI, significant changes are observed in magnetoresistance and Hall resistance. The classical two-band model analysis shows that both electron and hole concentration are significantly reduced. According to the calculated results, ion implantation leads to significant changes in the band structure and the Fermi surface of the WTe2. Our results indicate that defect engineering is an effective route of controlling the electronic properties of WTe2 devices.
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11
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Niu W, Du K, Wang S, Zhang M, Gao M, Chen Y, Liu H, Zhou W, Song F, Wang P, Xu Y, Wang X, Shen J, Zhang R. Intrinsic ferromagnetism and quantum transport transition in individual Fe-doped Bi 2Se 3 topological insulator nanowires. NANOSCALE 2017; 9:12372-12378. [PMID: 28612869 DOI: 10.1039/c7nr02807e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Time-reversal symmetry is broken by magnetic doping in topological insulators (TIs). An energy gap at the Dirac point opens and thus, generates numerous surface carriers. TI nanostructures are an ideal platform to investigate exotic surface transport behavior due to their large surface-to-volume ratio, which enhances the contribution of the TI surface states. However, magnetic doping into TI nanostructures has been challenging, and induced magnetic behavior has remained elusive. Herein, we have synthesized Fe-doped Bi2Se3 nanowires using a facile chemical vapor deposition with a doping concentration of ∼1 at%. The combined structural characterizations illustrate the homogeneous distribution of the Fe dopants. Cryogenic magnetic force microscopy gives direct evidence of the spontaneous magnetization with a Curie temperature of ∼40 K in a single nanowire. The transport measurements show a quantum transition from weak anti-localization to weak localization behavior. All the evidence indicates the existence of intrinsic ferromagnetism and gapped topological surface states in the TI nanowires, paving a way for future memory and magnetoelectric nanodevice applications.
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Affiliation(s)
- Wei Niu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China.
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12
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Sánchez-Barriga J, Ogorodnikov II, Kuznetsov MV, Volykhov AA, Matsui F, Callaert C, Hadermann J, Verbitskiy NI, Koch RJ, Varykhalov A, Rader O, Yashina LV. Observation of hidden atomic order at the interface between Fe and topological insulator Bi2Te3. Phys Chem Chem Phys 2017; 19:30520-30532. [DOI: 10.1039/c7cp04875k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first compelling evidence of unique atomic order at the ferromagnet Fe/topological insulator Bi2Te3 interface.
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Affiliation(s)
| | - Ilya I. Ogorodnikov
- Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences
- 620990 Ekaterinburg
- Russia
| | - Mikhail V. Kuznetsov
- Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences
- 620990 Ekaterinburg
- Russia
| | - Andrey A. Volykhov
- Department of Chemistry, Lomonosov Moscow State University
- 119991 Moscow
- Russia
- Kurnakov Institute of General and Inorganic Chemistry RAS
- 119991 Moscow
| | | | | | - Joke Hadermann
- EMAT, Department of Physics
- University of Antwerp
- 2020 Antwerp
- Belgium
| | | | - Roland J. Koch
- Advanced Light Source, Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Andrei Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie
- 12489 Berlin
- Germany
| | - Oliver Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie
- 12489 Berlin
- Germany
| | - Lada V. Yashina
- Department of Chemistry, Lomonosov Moscow State University
- 119991 Moscow
- Russia
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13
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Kim J, Jhi SH, Wu R. Engineering Topological Surface States of Cr-Doped Bi 2Se 3 Films by Spin Reorientation and Electric Field. NANO LETTERS 2016; 16:6656-6660. [PMID: 27668826 DOI: 10.1021/acs.nanolett.6b03439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The tailoring of topological surface states in topological insulators is essential for device applications and for exploring new topological phase. Here, we propose a practical way to induce the quantum anomalous Hall phase and unusual metal-insulator transitions in Cr-doped Bi2Se3 films based on the model Hamiltonian and first-principles calculations. Using the combination of in-plane and plane-normal components of the spin along with external electric fields, we demonstrate that the topological state and band structures of topological insulating films exhibit rich features such as the shift of Dirac cones and the opening of nontrivial band gaps. We also show that the in-plane magnetization leads to significant suppression of inter-TSS scattering in Cr-doped Bi2Se3. Our work provides new strategies to obtain the desired electronic structures for the device, complementary to the efforts of an extensive material search.
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Affiliation(s)
- Jeongwoo Kim
- Department of Physics and Astronomy, University of California , Irvine, California 92697, United States
| | - Seung-Hoon Jhi
- Department of Physics, Pohang University of Science and Technology , Pohang 790-784, Republic of Korea
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California , Irvine, California 92697, United States
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14
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Atomic-level structural and chemical analysis of Cr-doped Bi2Se3 thin films. Sci Rep 2016; 6:26549. [PMID: 27221782 PMCID: PMC4879552 DOI: 10.1038/srep26549] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 05/04/2016] [Indexed: 11/18/2022] Open
Abstract
We present a study of the structure and chemical composition of the Cr-doped 3D topological insulator Bi2Se3. Single-crystalline thin films were grown by molecular beam epitaxy on Al2O3 (0001), and their structural and chemical properties determined on an atomic level by aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy. A regular quintuple layer stacking of the Bi2Se3 film is found, with the exception of the first several atomic layers in the initial growth. The spectroscopy data gives direct evidence that Cr is preferentially substituting for Bi in the Bi2Se3 host. We also show that Cr has a tendency to segregate at internal grain boundaries of the Bi2Se3 film.
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15
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Liu W, West D, He L, Xu Y, Liu J, Wang K, Wang Y, van der Laan G, Zhang R, Zhang S, Wang KL. Atomic-Scale Magnetism of Cr-Doped Bi2Se3 Thin Film Topological Insulators. ACS NANO 2015; 9:10237-10243. [PMID: 26348798 DOI: 10.1021/acsnano.5b03980] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Magnetic doping is the most common method for breaking time-reversal-symmetry surface states of topological insulators (TIs) to realize novel physical phenomena and to create beneficial technological applications. Here we present a study of the magnetic coupling of a prototype magnetic TI, that is, Cr-doped Bi2Se3, in its ultrathin limit which is expected to give rise to quantum anomalous Hall (QAH) effect. The high quality Bi2-xCrxSe3 epitaxial thin film was prepared using molecular beam epitaxy (MBE), characterized with scanning transimission electron microscopy (STEM), electrical magnetotransport, and X-ray magnetic circularly dichroism (XMCD) techniques, and the results were simulated using density functional theory (DFT) with spin-orbit coupling (SOC). We observed a sizable spin moment mspin = (2.05 ± 0.20) μB/Cr and a small and negative orbital moment morb = (-0.05 ± 0.02) μB/Cr of the Bi1.94Cr0.06Se3 thin film at 2.5 K. A remarkable fraction of the (CrBi-CrI)(3+) antiferromagnetic dimer in the Bi2-xCrxSe3 for 0.02 < x < 0.40 was obtained using first-principles simulations, which was neglected in previous studies. The spontaneous coexistence of ferro- and antiferromagnetic Cr defects in Bi2-xCrxSe3 explains our experimental observations and those based on conventional magnetometry which universally report magnetic moments significantly lower than 3 μB/Cr predicted by Hund's rule.
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Affiliation(s)
- Wenqing Liu
- York-Nanjing Joint Center (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York YO10 5DD, United Kingdom
| | - Damien West
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Liang He
- York-Nanjing Joint Center (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
- Department of Electrical Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Yongbing Xu
- York-Nanjing Joint Center (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York YO10 5DD, United Kingdom
| | - Jun Liu
- Center of Electron Microscopy, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Kejie Wang
- York-Nanjing Joint Center (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
| | - Yong Wang
- Center of Electron Microscopy, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Gerrit van der Laan
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE, United Kingdom
| | - Rong Zhang
- York-Nanjing Joint Center (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
| | - Shengbai Zhang
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Kang L Wang
- Department of Electrical Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States
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