1
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Liang G, Zhai G, Ma J, Wang H, Zhao J, Wu X, Zhang X. Circular Photogalvanic Current in Ni-Doped Cd 3As 2 Films Epitaxied on GaAs(111)B Substrate. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:1979. [PMID: 37446495 DOI: 10.3390/nano13131979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/26/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023]
Abstract
Magnetic element doped Cd3As2 Dirac semimetal has attracted great attention for revealing the novel quantum phenomena and infrared opto-electronic applications. In this work, the circular photogalvanic effect (CPGE) was investigated at various temperatures for the Ni-doped Cd3As2 films which were grown on GaAs(111)B substrate by molecular beam epitaxy. The CPGE current generation was found to originate from the structural symmetry breaking induced by the lattice strain and magnetic doping in the Ni-doped Cd3As2 films, similar to that in the undoped ones. However, the CPGE current generated in the Ni-doped Cd3As2 films was approximately two orders of magnitude smaller than that in the undoped one under the same experimental conditions and exhibited a complex temperature variation. While the CPGE current in the undoped film showed a general increase with rising temperature. The greatly reduced CPGE current generation efficiency and its complex variation with temperature in the Ni-doped Cd3As2 films was discussed to result from the efficient capture of photo-generated carriers by the deep-level magnetic impurity bands and enhanced momentum relaxation caused by additional strong impurity scattering when magnetic dopants were introduced.
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Affiliation(s)
- Gaoming Liang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guihao Zhai
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jialin Ma
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hailong Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoguang Wu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xinhui Zhang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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2
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Wu W, Shi Z, Du Y, Wang Y, Qin F, Meng X, Liu B, Ma Y, Yan Z, Ozerov M, Zhang C, Lu HZ, Chu J, Yuan X. Topological Lifshitz transition and one-dimensional Weyl mode in HfTe 5. NATURE MATERIALS 2023; 22:84-91. [PMID: 36175521 DOI: 10.1038/s41563-022-01364-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 08/15/2022] [Indexed: 06/16/2023]
Abstract
Landau band crossings typically stem from the intra-band evolution of electronic states in magnetic fields and enhance the interaction effect in their vicinity. Here in the extreme quantum limit of topological insulator HfTe5, we report the observation of a topological Lifshitz transition from inter-band Landau level crossings using magneto-infrared spectroscopy. By tracking the Landau level transitions, we demonstrate that band inversion drives the zeroth Landau bands to cross with each other after 4.5 T and forms a one-dimensional Weyl mode with the fundamental gap persistently closed. The unusual reduction of the zeroth Landau level transition activity suggests a topological Lifshitz transition at 21 T, which shifts the Weyl mode close to the Fermi level. As a result, a broad and asymmetric absorption feature emerges due to the Pauli blocking effect in one dimension, along with a distinctive negative magneto-resistivity. Our results provide a strategy for realizing one-dimensional Weyl quasiparticles in bulk crystals.
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Affiliation(s)
- Wenbin Wu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China
| | - Zeping Shi
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China
| | - Yuhan Du
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China
| | - Yuxiang Wang
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai, China
| | - Fang Qin
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen, China
| | - Xianghao Meng
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China
| | - Binglin Liu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China
| | - Yuanji Ma
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China
| | - Zhongbo Yan
- School of Physics, Sun Yat-Sen University, Guangzhou, China
| | - Mykhaylo Ozerov
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - Cheng Zhang
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai, China.
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai, China.
| | - Hai-Zhou Lu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen, China
| | - Junhao Chu
- School of Physics and Electronic Science, East China Normal University, Shanghai, China
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai, China
- Institute of Optoelectronics, Fudan University, Shanghai, China
| | - Xiang Yuan
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
- School of Physics and Electronic Science, East China Normal University, Shanghai, China.
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Esin VD, Shvetsov OO, Timonina AV, Kolesnikov NN, Deviatov EV. Interface Superconductivity in a Dirac Semimetal NiTe 2. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:4114. [PMID: 36500737 PMCID: PMC9741339 DOI: 10.3390/nano12234114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/09/2022] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
We experimentally investigated charge transport through a single planar junction between a NiTe2 Dirac semimetal and a normal gold lead. At milli-Kelvin temperatures, we observe non-Ohmic dV/dI(V) behavior resembling Andreev reflection at a superconductor-normal metal interface, while NiTe2 bulk remains non-superconducting. The conclusion on superconductivity is also supported by the suppression of the effect by temperature and magnetic field. In analogy with the known results for Cd3As2 Dirac semimetal, we connect this behavior with interfacial superconductivity due to the flat-band formation at the Au-NiTe2 interface. Since the flat-band and topological surface states are closely connected, the claim on the flat-band-induced superconductivity is also supported by the Josephson current through the topological surface states on the pristine NiTe2 surface. We demonstrate the pronounced Josephson diode effect, which results from the momentum shift of the topological surface states of NiTe2 under an in-plane magnetic field.
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4
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Murotani Y, Kanda N, Ikeda TN, Matsuda T, Goyal M, Yoshinobu J, Kobayashi Y, Stemmer S, Matsunaga R. Stimulated Rayleigh Scattering Enhanced by a Longitudinal Plasma Mode in a Periodically Driven Dirac Semimetal Cd_{3}As_{2}. PHYSICAL REVIEW LETTERS 2022; 129:207402. [PMID: 36461987 DOI: 10.1103/physrevlett.129.207402] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 07/06/2022] [Accepted: 10/17/2022] [Indexed: 06/17/2023]
Abstract
Using broadband (12-45 THz) multi-terahertz spectroscopy, we show that stimulated Rayleigh scattering dominates the transient optical conductivity of cadmium arsenide, a Dirac semimetal, under an optical driving field at 30 THz. The characteristic dispersive line shape with net optical gain is accounted for by optical transitions between light-induced Floquet subbands, strikingly enhanced by the longitudinal plasma mode. Stimulated Rayleigh scattering with an unprecedentedly large refractive index change may pave the way for slow light generation in conductive solids at room temperature.
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Affiliation(s)
- Yuta Murotani
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Natsuki Kanda
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Tatsuhiko N Ikeda
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Takuya Matsuda
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Manik Goyal
- Materials Department, University of California, Santa Barbara, California 93106-5050, USA
| | - Jun Yoshinobu
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yohei Kobayashi
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Susanne Stemmer
- Materials Department, University of California, Santa Barbara, California 93106-5050, USA
| | - Ryusuke Matsunaga
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
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5
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Liang G, Zhai G, Ma J, Wang H, Zhao J, Wu X, Zhang X. Ultrafast Optical Probe of Coherent Acoustic Phonons in Dirac Semimetal Cd 3As 2 Film Epitaxied on GaAs(111)B Substrate. J Phys Chem Lett 2022; 13:8783-8792. [PMID: 36103381 DOI: 10.1021/acs.jpclett.2c02301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Coherent longitudinal acoustic phonon (CAP) generation in epitaxial Dirac semimetal Cd3As2 films with different thicknesses was investigated by a time-resolved reflectance technique. The short-lived weak CAP oscillations can be observed only in the thicker Cd3As2 films, and their central frequency of 0.039 THz has no dependence on sample thickness, but is nearly inversely proportional to the probe wavelength. For the 20 nm thin film, the observed long-lived CAP with a central frequency of 0.049 THz is generated in the GaAs(111)B substrate underneath. A sound velocity of 3800 m/s for the Cd3As2 film and 5360 m/s for the GaAs(111)B substrate is thus deduced. In addition, the opposite CAP amplitude and lifetime dependence on temperature further confirms the electronic and thermal stress origination of CAP generated in GaAs(111)B and Cd3As2 film, respectively, based on the propagating strain pulse model. The central frequency of CAP is found to be stable with increasing pumping fluence and temperature, which makes Cd3As2 a potential material for thermoelectric device applications.
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Affiliation(s)
- Gaoming Liang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, PR China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Guihao Zhai
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, PR China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Jialin Ma
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, PR China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Hailong Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, PR China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, PR China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Xiaoguang Wu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, PR China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Xinhui Zhang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, PR China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, PR China
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6
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Ultrafast photothermoelectric effect in Dirac semimetallic Cd 3As 2 revealed by terahertz emission. Nat Commun 2022; 13:1623. [PMID: 35338125 PMCID: PMC8956572 DOI: 10.1038/s41467-022-29168-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/17/2022] [Indexed: 11/18/2022] Open
Abstract
The thermoelectric effects of topological semimetals have attracted tremendous research interest because many topological semimetals are excellent thermoelectric materials and thermoelectricity serves as one of their most important potential applications. In this work, we reveal the transient photothermoelectric response of Dirac semimetallic Cd3As2, namely the photo-Seebeck effect and photo-Nernst effect, by studying the terahertz (THz) emission from the transient photocurrent induced by these effects. Our excitation polarization and power dependence confirm that the observed THz emission is due to photothermoelectric effect instead of other nonlinear optical effect. Furthermore, when a weak magnetic field (~0.4 T) is applied, the response clearly indicates an order of magnitude enhancement on transient photothermoelectric current generation compared to the photo-Seebeck effect. Such enhancement supports an ambipolar transport nature of the photo-Nernst current generation in Cd3As2. These results highlight the enhancement of thermoelectric performance can be achieved in topological Dirac semimetals based on the Nernst effect, and our transient studies pave the way for thermoelectric devices applicable for high field circumstance when nonequilibrium state matters. The large THz emission due to highly efficient photothermoelectric conversion is comparable to conventional semiconductors through optical rectification and photo-Dember effect. Many topological semimetals are excellent thermoelectric materials, but previous studies were limited to steady-state properties. Here, the authors observe a transient thermoelectric response in Cd3As2 by detecting the resulting THz emission, with an enhanced response when a small magnetic field is applied.
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7
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Kanda N, Murotani Y, Matsuda T, Goyal M, Salmani-Rezaie S, Yoshinobu J, Stemmer S, Matsunaga R. Tracking Ultrafast Change of Multiterahertz Broadband Response Functions in a Photoexcited Dirac Semimetal Cd 3As 2 Thin Film. NANO LETTERS 2022; 22:2358-2364. [PMID: 35285654 DOI: 10.1021/acs.nanolett.1c04890] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The electromagnetic response of Dirac semimetals in the infrared and terahertz frequency ranges is attracting growing interest for potential applications in optoelectronics and nonlinear optics. The interplay between the free-carrier response and interband transitions in the gapless, linear dispersion relation plays a key role in enabling novel functionalities. Here we investigate ultrafast dynamics in thin films of a photoexcited Dirac semimetal Cd3As2 by probing the broadband response functions as complex quantities in the multiterahertz region (10-45 THz, 40-180 meV, or 7-30 μm), which covers the crossover between the inter- and intraband response. We resolve dynamics of the photoexcited nonthermal electrons, which merge with originally existing carriers to form a single thermalized electron gas and how it is facilitated by high-density excitation. We also demonstrate that a large reduction of the refractive index by 80% dominates the nonequilibrium infrared response, which can be utilized for designing ultrafast switches in active optoelectronics.
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Affiliation(s)
- Natsuki Kanda
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Yuta Murotani
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Takuya Matsuda
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Manik Goyal
- Materials Department, University of California, Santa Barbara, California 93106-5050, United States
| | - Salva Salmani-Rezaie
- Materials Department, University of California, Santa Barbara, California 93106-5050, United States
| | - Jun Yoshinobu
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Susanne Stemmer
- Materials Department, University of California, Santa Barbara, California 93106-5050, United States
| | - Ryusuke Matsunaga
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
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8
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Liang G, Zhai G, Ma J, Wang H, Zhao J, Wu X, Zhang X. Strain-induced circular photogalvanic current in Dirac semimetal Cd 3As 2 films epitaxied on a GaAs(111)B substrate. NANOSCALE 2022; 14:2383-2392. [PMID: 35088779 DOI: 10.1039/d1nr05812f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Dirac semimetal (DSM) Cd3As2 has drawn great attention for exploring the novel quantum phenomena and high-speed optoelectronic applications. The circular photogalvanic effect (CPGE) current, resulting from the optically-excited spin orientation transport, was theoretically predicted to vanish in an ideal Dirac system due to the symmetric photoexcitation about the Dirac point. Here, we reported the observation of the CPGE photocurrent in epitaxial Cd3As2 thin films grown on a GaAs(111)B substrate. The signature of the CPGE is confirmed by its sign reversal upon switching the helicity of optical radiation, as well as its dependence on the excitation incident angle and power. By comparison of the CPGE response between the films with different thicknesses, it is suggested that the observed CPGE results from the reduced structure symmetry and substantially modified electronic band structure of the Cd3As2 thin film that undergoes large epitaxial strain. Our experimental findings provide a valuable reference for the band engineering and exotic helicity-dependent photocurrent phenomena in DSMs towards their potential opto-spintronic device applications.
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Affiliation(s)
- Gaoming Liang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Guihao Zhai
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jialin Ma
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Hailong Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Xiaoguang Wu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Xinhui Zhang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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9
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Cheng B, Schumann T, Stemmer S, Armitage NP. Probing charge pumping and relaxation of the chiral anomaly in a Dirac semimetal. SCIENCE ADVANCES 2021; 7:eabg0914. [PMID: 33863734 PMCID: PMC8051870 DOI: 10.1126/sciadv.abg0914] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 03/01/2021] [Indexed: 06/12/2023]
Abstract
The linear band crossings of 3D Dirac and Weyl semimetals are characterized by a charge chirality, the parallel or antiparallel locking of electron spin to its momentum. These materials are believed to exhibit an E · B chiral magnetic effect that is associated with the near conservation of chiral charge. Here, we use magneto-terahertz spectroscopy to study epitaxial Cd3As2 films and extract their conductivities σ(ω) as a function of E · B. As field is applied, we observe a markedly sharp Drude response that rises out of the broader background. Its appearance is a definitive signature of a new transport channel and consistent with the chiral response, with its spectral weight a measure of the net chiral charge and width a measure of the scattering rate between chiral species. The field independence of the chiral relaxation establishes that it is set by the approximate conservation of the isospin that labels the crystalline point-group representations.
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Affiliation(s)
- Bing Cheng
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Timo Schumann
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Susanne Stemmer
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - N P Armitage
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA.
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10
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Abstract
We present a theoretical study of the band structure and optical conductivity for the chiral multifold semimetal PdGa. We identify several characteristic features in the optical conductivity and provide their origins within the band structure. As experimental optical studies for the mentioned compound have not been reported, we contrast our results with the related compounds, RhSi and CoSi. We believe that the presented hallmarks will provide guidance to future experimental works.
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11
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Xu B, Fang Z, Sánchez-Martínez MÁ, Venderbos JWF, Ni Z, Qiu T, Manna K, Wang K, Paglione J, Bernhard C, Felser C, Mele EJ, Grushin AG, Rappe AM, Wu L. Optical signatures of multifold fermions in the chiral topological semimetal CoSi. Proc Natl Acad Sci U S A 2020; 117:27104-27110. [PMID: 33077590 PMCID: PMC7959492 DOI: 10.1073/pnas.2010752117] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report the optical conductivity in high-quality crystals of the chiral topological semimetal CoSi, which hosts exotic quasiparticles known as multifold fermions. We find that the optical response is separated into several distinct regions as a function of frequency, each dominated by different types of quasiparticles. The low-frequency intraband response is captured by a narrow Drude peak from a high-mobility electron pocket of double Weyl quasiparticles, and the temperature dependence of the spectral weight is consistent with its Fermi velocity. By subtracting the low-frequency sharp Drude and phonon peaks at low temperatures, we reveal two intermediate quasilinear interband contributions separated by a kink at 0.2 eV. Using Wannier tight-binding models based on first-principle calculations, we link the optical conductivity above and below 0.2 eV to interband transitions near the double Weyl fermion and a threefold fermion, respectively. We analyze and determine the chemical potential relative to the energy of the threefold fermion, revealing the importance of transitions between a linearly dispersing band and a flat band. More strikingly, below 0.1 eV our data are best explained if spin-orbit coupling is included, suggesting that at these energies, the optical response is governed by transitions between a previously unobserved fourfold spin-3/2 node and a Weyl node. Our comprehensive combined experimental and theoretical study provides a way to resolve different types of multifold fermions in CoSi at different energy. More broadly, our results provide the necessary basis to interpret the burgeoning set of optical and transport experiments in chiral topological semimetals.
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Affiliation(s)
- Bing Xu
- Fribourg Center for Nanomaterials, Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Zhenyao Fang
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323
| | | | - Jorn W F Venderbos
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104
- Department of Physics, Drexel University, Philadelphia, PA 19104
- Department of Materials Science and Engineering, Drexel University, Philadelphia, PA 19104
| | - Zhuoliang Ni
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104
| | - Tian Qiu
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323
| | - Kaustuv Manna
- Max Planck Institut fur Chemische Physik fester Stoffe, 01187 Dresden, Germany
| | - Kefeng Wang
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD 20742
| | - Johnpierre Paglione
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD 20742
- Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
| | - Christian Bernhard
- Fribourg Center for Nanomaterials, Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Claudia Felser
- Max Planck Institut fur Chemische Physik fester Stoffe, 01187 Dresden, Germany
- Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
| | - Eugene J Mele
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104
| | - Adolfo G Grushin
- Institut Néel, CNRS and Université Grenoble Alpes, 38042 Grenoble, France
| | - Andrew M Rappe
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323
| | - Liang Wu
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104;
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12
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Morphology and Optical Properties of Thin Cd3As2 Films of a Dirac Semimetal Compound. METALS 2020. [DOI: 10.3390/met10101398] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Using atomic-force microscopy (AFM) and wide-band (0.02–8.5 eV) spectroscopic ellipsometry techniques, we investigated the morphology and optical properties of Cd3As2 films grown by non-reactive RF magnetron sputtering on two types of oriented crystalline substrates (100)p-Si and (001) α-Al2O3. The AFM study revealed the grainy morphology of the films due to island incorporation during the film growth. The complex dielectric function spectra of the annealed Cd3As2/Al2O3 films manifest pronounced interband optical transitions at 1.2 and 3.0 eV, in excellent agreement with the theoretical calculations for the body centered tetragonal Cd3As2 crystal structure. We discovered that due to electronic excitations to the Cd(s) conical bands, the low-energy absorption edge of the annealed Cd3As2 films reveals a linear dependence. We found that for the annealed Cd3As2 films, the Cd(s) conical node may be shifted in energy by about 0.08–0.18 eV above the heavy-flat As(p) valence band, determining the optical gap value. The as-grown Cd3As2 films exhibit the pronounced changes of the electronic band structure due to the doping effect associated with Cd non-stoichiometry, where fine-tuning of the Cd concentration may result in the gapless electronic band structure of Dirac semimetals.
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13
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Krishtopenko SS, Antezza M, Teppe F. Hybridization of topological surface states with a flat band. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:165501. [PMID: 31899908 DOI: 10.1088/1361-648x/ab6741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We address the problem of hybridization between topological surface states and a non-topological flat bulk band. Our model, being a mixture of three-dimensional Bernevig-Hughes-Zhang and two-dimensional pseudospin-1 Hamiltonian, allows explicit treatment of the topological surface state evolution by continuously changing the hybridization between the inverted bands and an additional 'parasitic' flat band in the bulk. We show that the hybridization with a flat band lying below the edge of the conduction band converts the initial Dirac-like surface states into a branch below and one above the flat band. Our results univocally demonstrate that the upper branch of the topological surface states is formed by Dyakonov-Khaetskii surface states, known for HgTe since the 1980s. Additionally we explore an evolution of the surface states and the arising of Fermi arcs in Dirac semimetals when the flat band crosses the conduction band.
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Affiliation(s)
- Sergey S Krishtopenko
- Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-Université de Montpellier, F-34095 Montpellier, France
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14
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Cheng B, Kanda N, Ikeda TN, Matsuda T, Xia P, Schumann T, Stemmer S, Itatani J, Armitage NP, Matsunaga R. Efficient Terahertz Harmonic Generation with Coherent Acceleration of Electrons in the Dirac Semimetal Cd_{3}As_{2}. PHYSICAL REVIEW LETTERS 2020; 124:117402. [PMID: 32242712 DOI: 10.1103/physrevlett.124.117402] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/17/2020] [Accepted: 02/21/2020] [Indexed: 05/27/2023]
Abstract
We report strong terahertz (∼10^{12} Hz) high harmonic generation at room temperature in thin films of Cd_{3}As_{2}, a three-dimensional Dirac semimetal. Third harmonics are detectable with a tabletop light source and can be as strong as 100 V/cm by applying a fundamental field of 6.5 kV/cm inside the film, demonstrating an unprecedented efficiency for terahertz frequency conversion. Our time-resolved terahertz spectroscopy and calculations also clarify the microscopic mechanism of the nonlinearity originating in the coherent acceleration of Dirac electrons in momentum space. Our results provide clear insights for nonlinear currents of Dirac electrons driven by the terahertz field under the influence of scattering, paving the way toward novel devices for high-speed electronics and photonics based on topological semimetals.
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Affiliation(s)
- Bing Cheng
- The Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Natsuki Kanda
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Tatsuhiko N Ikeda
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Takuya Matsuda
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Peiyu Xia
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Timo Schumann
- Materials Department, University of California, Santa Barbara, California 93106-5050, USA
| | - Susanne Stemmer
- Materials Department, University of California, Santa Barbara, California 93106-5050, USA
| | - Jiro Itatani
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - N P Armitage
- The Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Ryusuke Matsunaga
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
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15
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Bonačić Lošić Ž. The coupling effects of surface plasmons and Fermi arc plasmons in Weyl semimetals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:285001. [PMID: 30959499 DOI: 10.1088/1361-648x/ab1734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We study the effects of coupling between surface plasmon and Fermi arc plasmon modes on a planar surface of the Weyl semimetal. A model Hamiltonian is proposed in the second quantization representation for the system of coupled surface plasmon and Fermi arc plasmon modes. We obtain the dispersion relations of coupled modes using the Bogoliubov transformation technique. We identify the upper coupled mode as the renormalized surface plasmon and the lower coupled mode as the renormalized Fermi arc plasmon. It is shown how the magnitude of the coupling depends on both the bare mode dispersions and their dampings. We also demonstrate that coupling increases the surface plasmon mode lifetime. Obtained results for the surface plasmon mode are qualitatively consistent with the recent experimental data of Weyl semimetals.
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16
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Roy B, Juričić V. Collisionless Transport Close to a Fermionic Quantum Critical Point in Dirac Materials. PHYSICAL REVIEW LETTERS 2018; 121:137601. [PMID: 30312062 DOI: 10.1103/physrevlett.121.137601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Indexed: 06/08/2023]
Abstract
Quantum transport close to a critical point is a fundamental, but enigmatic problem due to fluctuations, persisting at all length scales. We report the scaling of optical conductivity (OC) in the collisionless regime (ℏω≫k_{B}T) in the vicinity of a relativistic quantum critical point, separating two-dimensional (d=2) massless Dirac fermions from a fully gapped insulator or superconductor. Close to such a critical point, gapless fermionic and bosonic excitations are strongly coupled, leading to a universal suppression of the interband OC as well as of the Drude peak (while maintaining its delta function profile) inside the critical regime, which we compute to the leading order in 1/N_{f}- and ε expansions, where N_{f} counts the fermion flavor number and ε=3-d. Correction to the OC at such a non-Gaussian critical point due to the long-range Coulomb interaction and generalizations of these scenarios to a strongly interacting three-dimensional Dirac or Weyl liquid are also presented, which can be tested numerically and possibly from nonperturbative gauge-gravity duality, for example.
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Affiliation(s)
- Bitan Roy
- Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Strasse 38, 01187 Dresden, Germany
| | - Vladimir Juričić
- Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, 10691 Stockholm, Sweden
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17
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Bonačić Lošić Ž. Surface plasmons in Weyl semimetals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:365003. [PMID: 30063027 DOI: 10.1088/1361-648x/aad6f5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The surface plasmon excitation spectrum is calculated for the Weyl semimetal within the random phase approximation. Recently, a surface plasmon mode has been predicted to exist at the three-dimensional Dirac semimetal surface due to the Dirac plasmon mode in the bulk. In addition, Weyl semimetals possess Fermi arc electron states on their surfaces resulting in an anisotropic Fermi arc plasmon mode. In the present work we consider the modification of the surface plasmon mode due to the Fermi arc plasmon mode. We introduce an effective surface dielectric function of Fermi arc electrons which comprises the Fermi arc plasmon mode and the surface dielectric function that determines the bare surface plasmon mode present due to the plasmon mode in the bulk from Weyl electrons. As a result, we obtain the dispersion of the renormalized surface plasmon mode from the effective surface dielectric function. We find that a renormalization of the bare surface plasmon mode increases with increases in the Fermi arc plasmon frequency. The obtained spectrum will be useful for experimentally exploring the surface spectral properties of Weyl semimetals.
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18
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Yuan X, Yan Z, Song C, Zhang M, Li Z, Zhang C, Liu Y, Wang W, Zhao M, Lin Z, Xie T, Ludwig J, Jiang Y, Zhang X, Shang C, Ye Z, Wang J, Chen F, Xia Z, Smirnov D, Chen X, Wang Z, Yan H, Xiu F. Chiral Landau levels in Weyl semimetal NbAs with multiple topological carriers. Nat Commun 2018; 9:1854. [PMID: 29748535 PMCID: PMC5945645 DOI: 10.1038/s41467-018-04080-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 04/04/2018] [Indexed: 11/09/2022] Open
Abstract
Recently, Weyl semimetals have been experimentally discovered in both inversion-symmetry-breaking and time-reversal-symmetry-breaking crystals. The non-trivial topology in Weyl semimetals can manifest itself with exotic phenomena, which have been extensively investigated by photoemission and transport measurements. Despite the numerous experimental efforts on Fermi arcs and chiral anomaly, the existence of unconventional zeroth Landau levels, as a unique hallmark of Weyl fermions, which is highly related to chiral anomaly, remains elusive owing to the stringent experimental requirements. Here, we report the magneto-optical study of Landau quantization in Weyl semimetal NbAs. High magnetic fields drive the system toward the quantum limit, which leads to the observation of zeroth chiral Landau levels in two inequivalent Weyl nodes. As compared to other Landau levels, the zeroth chiral Landau level exhibits a distinct linear dispersion in magnetic field direction and allows the optical transitions without the limitation of zero z momentum or [Formula: see text] magnetic field evolution. The magnetic field dependence of the zeroth Landau levels further verifies the predicted particle-hole asymmetry of the Weyl cones. Meanwhile, the optical transitions from the normal Landau levels exhibit the coexistence of multiple carriers including an unexpected massive Dirac fermion, pointing to a more complex topological nature in inversion-symmetry-breaking Weyl semimetals. Our results provide insights into the Landau quantization of Weyl fermions and demonstrate an effective tool for studying complex topological systems.
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Affiliation(s)
- Xiang Yuan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China
| | - Zhongbo Yan
- Institute for Advanced Study, Tsinghua University, 100084, Beijing, China
| | - Chaoyu Song
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China
| | - Mengyao Zhang
- International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China.,Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
| | - Zhilin Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China.,Collaborative Innovation Center of Quantum Matter, 100871, Beijing, China
| | - Cheng Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China
| | - Yanwen Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China
| | - Weiyi Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China
| | - Minhao Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China
| | - Zehao Lin
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China
| | - Tian Xie
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China
| | - Jonathan Ludwig
- National High Magnetic Field Laboratory, Tallahassee, Florida, 32310, USA
| | - Yuxuan Jiang
- National High Magnetic Field Laboratory, Tallahassee, Florida, 32310, USA
| | - Xiaoxing Zhang
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, 430074, Wuhan, China
| | - Cui Shang
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, 430074, Wuhan, China
| | - Zefang Ye
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China
| | - Jiaxiang Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China
| | - Feng Chen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China
| | - Zhengcai Xia
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, 430074, Wuhan, China
| | - Dmitry Smirnov
- National High Magnetic Field Laboratory, Tallahassee, Florida, 32310, USA
| | - Xiaolong Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China.,Collaborative Innovation Center of Quantum Matter, 100871, Beijing, China
| | - Zhong Wang
- Institute for Advanced Study, Tsinghua University, 100084, Beijing, China.,Collaborative Innovation Center of Quantum Matter, 100871, Beijing, China
| | - Hugen Yan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China. .,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China.
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China. .,Collaborative Innovation Center of Advanced Microstructures, Fudan University, 200433, Shanghai, China. .,Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, 200433, Shanghai, China.
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19
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Wang A, Zhao X, Zhao M, Zhang X, Feng Y, Liu F. Kane Fermion in a Two-Dimensional π-Conjugated Bis(iminothiolato)nickel Monolayer. J Phys Chem Lett 2018; 9:614-619. [PMID: 29343066 DOI: 10.1021/acs.jpclett.7b03021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Massless Kane fermions revealed in zinc-blende semiconductors have recently gained interest in the broad study of relativistic materials. In particular, two-dimensional (2D) Kane fermions were expected to be hybrids of pseudospin-1 and -1/2 Dirac fermions. Based on first-principles calculations, we demonstrated that 2D Kane fermions can be realized in a recently synthesized metal-organic framework, namely, bis(iminothiolato)nickel monolayer. A slight compression takes the system from a semimetal to a semiconductor. At the critical strain of ∼1%, the upper and lower conical bands linearize and touch at a single point intersecting a flat band, showing the same dispersion as the pseudospin-1 Dirac-Weyl systems. We adopted a tight-binding Hamiltonian of a line-centered honeycomb lattice to reveal the origins and topology of the electronic band structure. The coexistence of Kane-type and Dirac-type spectra in the bis(iminothiolato)nickel monolayer is expected to benefit the study of multi quasiparticle effects.
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Affiliation(s)
- Aizhu Wang
- School of Physics and State Key Laboratory of Crystal Materials, Shandong University , Jinan, 250100, Shandong, China
- Department of Electrical and Computer Engineering & Department of Physics, National University of Singapore , Singapore, 117579, Singapore
| | - Xinrui Zhao
- School of the Gifted Young, University of Science and Technology of China , Hefei, 230026, Anhui, China
| | - Mingwen Zhao
- School of Physics and State Key Laboratory of Crystal Materials, Shandong University , Jinan, 250100, Shandong, China
| | - Xiaoming Zhang
- School of Physics and State Key Laboratory of Crystal Materials, Shandong University , Jinan, 250100, Shandong, China
| | - Yuanping Feng
- Department of Physics & Centre for Advanced Two-dimensional Materials, National University of Singapore , Singapore, 117542, Singapore
| | - Feng Liu
- Department of Materials Science and Engineering, University of Utah , Salt Lake City, Utah 84112, United States
- Collaborative Innovation Center of Quantum Matter , Beijing, 100084, Beijing, China
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20
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Lošić ŽB. Surface plasmon of three-dimensional Dirac semimetals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:045002. [PMID: 29219838 DOI: 10.1088/1361-648x/aaa070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The surface plasmon excitation spectrum is calculated for the semi-infinite 3D Dirac semimetal. We used the random phase approximation for the calculation of the surface dielectric function, from which we derived the dynamical structure factor. The surface excitation spectrum shows a well-defined strong surface plasmon peak due to the plasmon mode in the bulk, with a noticeable influence of electron-hole excitations at large wave vectors parallel to the surface. The obtained spectrum will be useful for experimentally exploring the surface spectral properties of 3D topological Dirac semimetals.
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21
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Chen ZG, Wang L, Song Y, Lu X, Luo H, Zhang C, Dai P, Yin Z, Haule K, Kotliar G. Two-Dimensional Massless Dirac Fermions in Antiferromagnetic AFe_{2}As_{2} (A=Ba,Sr). PHYSICAL REVIEW LETTERS 2017; 119:096401. [PMID: 28949552 DOI: 10.1103/physrevlett.119.096401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Indexed: 06/07/2023]
Abstract
We report infrared studies of AFe_{2}As_{2} (A=Ba, Sr), two representative parent compounds of iron-arsenide superconductors, at magnetic fields (B) up to 17.5 T. Optical transitions between Landau levels (LLs) were observed in the antiferromagnetic states of these two parent compounds. Our observation of a sqrt[B] dependence of the LL transition energies, the zero-energy intercepts at B=0 T under the linear extrapolations of the transition energies and the energy ratio (∼2.4) between the observed LL transitions, combined with the linear band dispersions in two-dimensional (2D) momentum space obtained by theoretical calculations, demonstrates the existence of massless Dirac fermions in the antiferromagnet BaFe_{2}As_{2}. More importantly, the observed dominance of the zeroth-LL-related absorption features and the calculated bands with extremely weak dispersions along the momentum direction k_{z} indicate that massless Dirac fermions in BaFe_{2}As_{2} are 2D. Furthermore, we find that the total substitution of the barium atoms in BaFe_{2}As_{2} by strontium atoms not only maintains 2D massless Dirac fermions in this system, but also enhances their Fermi velocity, which supports that the Dirac points in iron-arsenide parent compounds are topologically protected.
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Affiliation(s)
- Zhi-Guo Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Luyang Wang
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
- Sate Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-Sen University, Guangzhou 510275, China
| | - Yu Song
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Xingye Lu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Chenglin Zhang
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Zhiping Yin
- Center of Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Kristjan Haule
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- DMFT-MatDeLab Center, Upton, New York 11973, USA
| | - Gabriel Kotliar
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- DMFT-MatDeLab Center, Upton, New York 11973, USA
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22
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Yuan X, Cheng P, Zhang L, Zhang C, Wang J, Liu Y, Sun Q, Zhou P, Zhang DW, Hu Z, Wan X, Yan H, Li Z, Xiu F. Direct Observation of Landau Level Resonance and Mass Generation in Dirac Semimetal Cd 3As 2 Thin Films. NANO LETTERS 2017; 17:2211-2219. [PMID: 28244324 DOI: 10.1021/acs.nanolett.6b04778] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Three-dimensional topological Dirac semimetals have hitherto stimulated unprecedented research interests as a new class of quantum materials. Breaking certain types of symmetries has been proposed to enable the manipulation of Dirac fermions, and that was soon realized by external modulations such as magnetic fields. However, an intrinsic manipulation of Dirac states, which is more efficient and desirable, remains a significant challenge. Here, we report a systematic study of quasi-particle dynamics and band evolution in Cd3As2 thin films with controlled chromium (Cr) doping by both magneto-infrared spectroscopy and electrical transport. We observe the √B relation of inter-Landau-level resonance in Cd3As2, an important signature of ultrarelativistic massless state inaccessible in previous optical experiments. A crossover from quantum to quasi-classical behavior makes it possible to directly probe the mass of Dirac fermions. Importantly, Cr doping allows for a Dirac mass acquisition and topological phase transition enabling a desired dynamic control of Dirac fermions. Corroborating with the density-functional theory calculations, we show that the mass generation can be explained by the explicit C4 rotation symmetry breaking and the resultant Dirac gap engineering through Cr substitution for Cd atoms. The manipulation of the system symmetry and Dirac mass in Cd3As2 thin films provides a tuning knob to explore the exotic states stemming from the parent phase of Dirac semimetals.
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Affiliation(s)
- Xiang Yuan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China
| | - Peihong Cheng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China
| | - Longqiang Zhang
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University , Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Cheng Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China
| | - Junyong Wang
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University , Shanghai 200241, China
| | - Yanwen Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China
| | - Qingqing Sun
- State Key Laboratory of ASIC and System, Department of Microelectronics, Fudan University , Shanghai 200433, China
| | - Peng Zhou
- State Key Laboratory of ASIC and System, Department of Microelectronics, Fudan University , Shanghai 200433, China
| | - David Wei Zhang
- State Key Laboratory of ASIC and System, Department of Microelectronics, Fudan University , Shanghai 200433, China
| | - Zhigao Hu
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University , Shanghai 200241, China
| | - Xiangang Wan
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University , Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Hugen Yan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China
| | - Zhiqiang Li
- College of Physical Science and Technology, Sichuan University , Chengdu, Sichuan 610064, China
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China
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23
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Mosca Conte A, Pulci O, Bechstedt F. Electronic and optical properties of topological semimetal Cd 3As 2. Sci Rep 2017; 7:45500. [PMID: 28383018 PMCID: PMC5382546 DOI: 10.1038/srep45500] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 02/27/2017] [Indexed: 11/09/2022] Open
Abstract
Using ab initio density functional theory the band structure and the dielectric function of a bct Cd3As2 crystal are calculated. We find a Dirac semimetal with two Dirac nodes k± near the Γ point on the tetragonal axis. The bands near the Fermi level exhibit a linear behavior. The resulting Dirac cones are anisotropic and the electron-hole symmetry is destroyed along the tetragonal axis. Along this axis the symmetry-protected band linearity only exists in a small energy interval. The Dirac cones seemingly found by ARPES in a wider energy range are interpreted in terms of pseudo-linear bands. The behavior as 3D graphene-like material is traced back to As p orbital pointing to Cd vacancies, in directions which vary throughout the unit cell. Because of the Dirac nodes the dielectric functions (imaginary part) show a plateau for vanishing frequencies whose finite value is proportional to the Sommerfeld fine structure constant but varies with the light polarization. The consequences of the anisotropy of the Dirac cones are highlighted for the polarization dependence of the infrared optical conductivity.
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Affiliation(s)
- Adriano Mosca Conte
- ISMN, Consiglio Nazionale delle Ricerche, Via Salaria Km 29,300 00015 Monterotondo Stazione (Roma) - Italy.,Dipartimento di Fisica, Università di Roma 'Tor Vergata', Via della Ricerca Scientifica 1, I-00133, Rome, Italy
| | - Olivia Pulci
- Dipartimento di Fisica, Università di Roma 'Tor Vergata', Via della Ricerca Scientifica 1, I-00133, Rome, Italy.,I.N.F.N, - Sezione di Roma 'Tor Vergata', and CNR-ISM, Roma, Italy
| | - Friedhelm Bechstedt
- IFTO, Friedrich-Schiller-Universität and ETSF, Max-Wien-Platz 1, 07743 Jena, Germany
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24
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Shao Y, Post KW, Wu JS, Dai S, Frenzel AJ, Richardella AR, Lee JS, Samarth N, Fogler MM, Balatsky AV, Kharzeev DE, Basov DN. Faraday Rotation Due to Surface States in the Topological Insulator (Bi 1-xSb x) 2Te 3. NANO LETTERS 2017; 17:980-984. [PMID: 28030948 DOI: 10.1021/acs.nanolett.6b04313] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Using magneto-infrared spectroscopy, we have explored the charge dynamics of (Bi,Sb)2Te3 thin films on InP substrates. From the magneto-transmission data we extracted three distinct cyclotron resonance (CR) energies that are all apparent in the broad band Faraday rotation (FR) spectra. This comprehensive FR-CR data set has allowed us to isolate the response of the bulk states from the intrinsic surface states associated with both the top and bottom surfaces of the film. The FR data uncovered that electron- and hole-type Dirac Fermions reside on opposite surfaces of our films, which paves the way for observing many exotic quantum phenomena in topological insulators.
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Affiliation(s)
- Yinming Shao
- Department of Physics, Columbia University , New York, New York 10027, United States
| | - Kirk W Post
- Physics Department, University of California-San Diego , La Jolla, California 92093, United States
| | - Jhih-Sheng Wu
- Physics Department, University of California-San Diego , La Jolla, California 92093, United States
| | - Siyuan Dai
- Physics Department, University of California-San Diego , La Jolla, California 92093, United States
| | - Alex J Frenzel
- Physics Department, University of California-San Diego , La Jolla, California 92093, United States
| | - Anthony R Richardella
- Department of Physics, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Joon Sue Lee
- Department of Physics, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Nitin Samarth
- Department of Physics, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Michael M Fogler
- Physics Department, University of California-San Diego , La Jolla, California 92093, United States
| | - Alexander V Balatsky
- Nordita, KTH Royal Institute of Technology and Stockholm University , Roslagstullsbacken 23, SE-106 91 Stockholm, Sweden
- Institute for Materials Science, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Dmitri E Kharzeev
- Department of Physics and Astronomy, Stony Brook University , Stony Brook, New York 11794-3800, United States
- Department of Physics and RIKEN-BNL Research Center, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - D N Basov
- Department of Physics, Columbia University , New York, New York 10027, United States
- Physics Department, University of California-San Diego , La Jolla, California 92093, United States
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