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Zhao A, Gu Q, Haugan TJ, Bullard TJ, Klemm RA. Type-II quantum spin Hall effect in two-dimensional metals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:485302. [PMID: 36191563 DOI: 10.1088/1361-648x/ac9720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 10/03/2022] [Indexed: 06/16/2023]
Abstract
The quantum spin Hall (QSH) effect has been observed in topological insulators and long quantum wells using spin-orbit coupling as the probe, but it has not yet been observed in a metal. An experiment is proposed to measure the different Type-II QSH effect of an electron or hole in a two-dimensional (2D) metal by using the previously unexplored but relativistically gauge-invariant form of the generated 2D QSH Hamiltonian. Instead of using the electric field in the surface of the spin-polarized bands of a topological insulator or across the quantum well width as the probe, ones uses an applied azimuthal vector potential and an applied radial electric field as the tools to generate a spontaneously quantized spin current in an otherwise spin unpolarized 2D metal. A long cylindrical solenoid lies normally through the inner radius of a 2D metallic Corbino disk. The currentISsurrounding the solenoid produces an azimuthal magnetic vector potential but no magnetic field in the disk. In addition, a radial electric field is generated across the disk by imposing either a potential differenceΔvor a radial charge currentIacross its inner and outer radii. Combined changes inISand in eitherΔvorIgenerate spontaneously quantized azimuthal charge and spin currents. The experiment is designed to measure these quantized azimuthal charge and spin currents in the disk consistently. The quantum Hamiltonians for both experiments are solved exactly. A method to control the Joule heating is presented, which could potentially allow the Type-II QSH measurements to be made at room temperature.
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Affiliation(s)
- Aiying Zhao
- Institute of Theoretical Physics, University of Science and Technology Beijing, Beijing 100083, People's Republic of China
- Department of Physics, University of Central Florida, Orlando, FL 32816-2385, United States of America
| | - Qiang Gu
- Institute of Theoretical Physics, University of Science and Technology Beijing, Beijing 100083, People's Republic of China
| | - Timothy J Haugan
- U. S. Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433-7251, United States of America
| | - Thomas J Bullard
- U. S. Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433-7251, United States of America
| | - Richard A Klemm
- Department of Physics, University of Central Florida, Orlando, FL 32816-2385, United States of America
- U. S. Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433-7251, United States of America
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Kashiwagi T, Yuasa T, Kuwano G, Yamamoto T, Tsujimoto M, Minami H, Kadowaki K. Study of Radiation Characteristics of Intrinsic Josephson Junction Terahertz Emitters with Different Thickness of Bi 2Sr 2CaCu 2O 8+δ Crystals. MATERIALS (BASEL, SWITZERLAND) 2021; 14:1135. [PMID: 33670854 PMCID: PMC7957731 DOI: 10.3390/ma14051135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/19/2021] [Accepted: 02/20/2021] [Indexed: 11/16/2022]
Abstract
The radiation intensity from the intrinsic Josephson junction high-Tc superconductor Bi2Sr2CaCu2O8+δ terahertz emitters (Bi2212-THz emitters) is one of the most important characteristics for application uses of the device. In principle, it would be expected to be improved with increasing the number of intrinsic Josephson junctions N in the emitters. In order to further improve the device characteristics, we have developed a stand alone type of mesa structures (SAMs) of Bi2212 crystals. Here, we understood the radiation characteristics of our SAMs more deeply, after we studied the radiation characteristics from three SAMs (S1, S2, and S3) with different thicknesses. Comparing radiation characteristics of the SAMs in which the number of intrinsic Josephson junctions are N∼ 1300 (S1), 2300 (S2), and 3100 (S3), respectively, the radiation intensity, frequency as well as the characteristics of the device working bath temperature are well understood. The strongest radiation of the order of few tens of microwatt was observed from the thickest SAM of S3. We discussed this feature through the N2-relationship and the radiation efficiency of a patch antenna. The thinner SAM of S1 can generate higher radiation frequencies than the thicker one of S3 due to the difference of the applied voltage per junctions limited by the heat-removal performance of the device structures. The observed features in this study are worthwhile designing Bi2212-THz emitters with better emission characteristics for many applications.
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Affiliation(s)
- Takanari Kashiwagi
- Graduate School of Pure & Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan; (T.Y.); (G.K.); (M.T.); (H.M.)
- Division of Materials Science, Faculty of Pure & Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8573, Japan
| | - Takumi Yuasa
- Graduate School of Pure & Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan; (T.Y.); (G.K.); (M.T.); (H.M.)
| | - Genki Kuwano
- Graduate School of Pure & Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan; (T.Y.); (G.K.); (M.T.); (H.M.)
| | - Takashi Yamamoto
- QuTech, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands;
| | - Manabu Tsujimoto
- Graduate School of Pure & Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan; (T.Y.); (G.K.); (M.T.); (H.M.)
- Division of Materials Science, Faculty of Pure & Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8573, Japan
| | - Hidetoshi Minami
- Graduate School of Pure & Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan; (T.Y.); (G.K.); (M.T.); (H.M.)
- Division of Materials Science, Faculty of Pure & Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8573, Japan
| | - Kazuo Kadowaki
- Algae Biomass and Energy System R & D Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8572, Japan;
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Cerkoney DP, Reid C, Doty CM, Gramajo A, Campbell TD, Morales MA, Delfanazari K, Tsujimoto M, Kashiwagi T, Yamamoto T, Watanabe C, Minami H, Kadowaki K, Klemm RA. Cavity mode enhancement of terahertz emission from equilateral triangular microstrip antennas of the high-T c superconductor Bi 2Sr 2CaCu 2O 8 + δ. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:015601. [PMID: 27830669 DOI: 10.1088/0953-8984/29/1/015601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We study the transverse magnetic (TM) electromagnetic cavity mode wave functions for an ideal equilateral triangular microstrip antenna (MSA) exhibiting C 3v point group symmetry. When the C 3v operations are imposed upon the antenna, the TM(m,n) modes with wave vectors [Formula: see text] are much less dense than commonly thought. The R 3 operations restrict the integral n and m to satisfy [Formula: see text], where [Formula: see text] and [Formula: see text] for the modes even and odd under reflections about the three mirror planes, respectively. We calculate the forms of representative wave functions and the angular dependence of the output power when these modes are excited by the uniform and non-uniform ac Josephson current sources in thin, ideally equilateral triangular MSAs employing the intrinsic Josephson junctions in the high transition temperature T c superconductor Bi2Sr2CaCu2 [Formula: see text], and fit the emissions data from an earlier sample for which the C 3v symmetry was apparently broken.
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Affiliation(s)
- Daniel P Cerkoney
- Department of Physics, University of Central Florida, 4000 Central Florida Blvd., Orlando, FL 32816-2385, USA
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