Article
Multidisciplinary Sciences
Jingyuan Zhong, Ming Yang, Zhijian Shi, Yaqi Li, Dan Mu, Yundan Liu, Ningyan Cheng, Wenxuan Zhao, Weichang Hao, Jianfeng Wang, Lexian Yang, Jincheng Zhuang, Yi Du
Summary: Weak topological insulators with tunable topological states are studied using ARPES and first-principles calculations. The authors find signatures of layer-selective quantum spin Hall channels in a candidate weak topological insulator, Bi4Br2I2, which is stacked by three different quantum spin Hall insulators. The energy gap at the crossing points of different Dirac cones, induced by interlayer interaction, enables the tunability of topological edge states. This work offers a perspective for constructing tunable quantized conductance devices for future spintronic applications.
NATURE COMMUNICATIONS
(2023)
Article
Quantum Science & Technology
Yi-Ping Wang, He Wang
Summary: We propose a theoretical method to study the topological properties of spin-phonon coupled modes in a one-dimensional superconducting resonator lattice. Different topological structures can be displayed by adjusting the coupling parameters, and the topological index of the system's phases can be distinguished.
QUANTUM INFORMATION PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Vladimir A. Zyuzin, Alexander M. Finkel'stein
Summary: In this study, we consider a two-dimensional disordered conductor in the presence of a magnetic field that destroys the superconducting phase. By analyzing a combination of fluctuations of different origin, we observe that the end of superconductivity corresponds to a quantum critical point separating the conventional superconducting phase from a state with odd-frequency spin-triplet pairing instability. This finding may provide insights into the mysterious insulating state observed in strongly disordered superconducting films across a wide range of magnetic fields.
Article
Chemistry, Physical
Nana Shumiya, Md Shafayat Hossain, Jia-Xin Yin, Zhiwei Wang, Maksim Litskevich, Chiho Yoon, Yongkai Li, Ying Yang, Yu-Xiao Jiang, Guangming Cheng, Yen-Chuan Lin, Qi Zhang, Zi-Jia Cheng, Tyler A. Cochran, Daniel Multer, Xian P. Yang, Brian Casas, Tay-Rong Chang, Titus Neupert, Zhujun Yuan, Shuang Jia, Hsin Lin, Nan Yao, Luis Balicas, Fan Zhang, Yugui Yao, M. Zahid Hasan
Summary: This study provides micro-spectroscopic evidence for the presence of a room-temperature quantum spin Hall edge state on the surface of a higher-order topological insulator. The research reveals the microstructural features of the topological phase and suggests further exploration of high-temperature transport quantization.
Article
Nanoscience & Nanotechnology
Yinong Zhou, Gurjyot Sethi, Hang Liu, Zhengfei Wang, Feng Liu
Summary: This article proposes theoretical concepts and models to describe the excited quantum anomalous Hall effect and quantum spin Hall effect generated by the dissociation of an excitonic insulator state. These effects are based on the nontrivial band topology and complete population inversion in 2D materials, and have important scientific significance and potential applications.
Article
Multidisciplinary Sciences
Matthew Weiner, Xiang Ni, Andrea Alu, Alexander B. Khanikaev
Summary: This study experimentally demonstrates the control of sound waves through material design in two types of acoustic systems. One method involves the excitation of transverse angular momentum in evanescent sound waves in perforated films, while the other method involves the excitation of synthetic transverse pseudo-spin through the lattice symmetries of an acoustic kagome lattice. These results offer new design approaches for acoustic devices.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Chi Xuan Trang, Qile Li, Yuefeng Yin, Jinwoong Hwang, Golrokh Akhgar, Iolanda Di Bernardo, Antonija Grubisic-Cabo, Anton Tadich, Michael S. Fuhrer, Sung-Kwan Mo, Nikhil Medhekar, Mark T. Edmonds
Summary: This study used temperature-dependent angle-resolved photoemission spectroscopy to investigate ultrathin MnBi2Te4, revealing a temperature-dependent magnetic topological phase transition that can be achieved at higher temperatures.
Article
Materials Science, Multidisciplinary
Xuguang Wang, Daiyu Geng, Dayu Yan, Wenqi Hu, Hexu Zhang, Shaosheng Yue, Zhenyu Sun, Shiv Kumar, Eike F. Schwier, Kenya Shimada, Peng Cheng, Lan Chen, Simin Nie, Zhijun Wang, Youguo Shi, Yi-Qi Zhang, Kehui Wu, Baojie Feng
Summary: Experimental evidence of a 2DTI in the van der Waals material Ta2Pd3Te5 has been reported, showing that each monolayer is a 2DTI with weak interlayer interactions. Measurements confirm the existence of a band gap at the Fermi level and topological edge states inside the gap, making Ta2Pd3Te5 a promising material for fabricating spintronic devices based on the QSH effect.
Article
Materials Science, Multidisciplinary
Ru Zheng, Rong-Qiang He, Zhong-Yi Lu
Summary: The interaction between two spins at the edge of a quantum spin Hall insulator was studied, along with the magnetic correlation between two Kondo impurities in a graphene nanoribbon with spin-orbital coupling. The study revealed how the spatial symmetry and anisotropy in the magnetic correlation were affected by the strength of SOC and the position of the impurities, demonstrating the effectiveness of NORG in studying quantum impurity systems.
Article
Chemistry, Multidisciplinary
Qi Gong, Guiling Zhang
Summary: This study investigates the electronic structures and stability of organic-group functionalized antimony and bismuth monolayers. The results show that these materials have a large electronic band-gap and nontrivial topology, making them suitable for spintronic devices based on the quantum spin Hall effect at room temperature.
Article
Physics, Multidisciplinary
C. L. Tschirhart, Evgeny Redekop, Lizhong Li, Tingxin Li, Shengwei Jiang, T. Arp, O. Sheekey, Takashi Taniguchi, Kenji Watanabe, M. E. Huber, Kin Fai Mak, Jie Shan, A. F. Young
Summary: Magnetic switching via spin-orbit torque is demonstrated in a moire bilayer, providing a platform for spintronic applications.
Article
Materials Science, Multidisciplinary
G. A. R. van Dalum, C. Ortix, L. Fritz
Summary: In this paper, a one-dimensional insulator with approximate chiral symmetry belonging to the AIII class was constructed by intentionally polluting the edge of a two-dimensional quantum spin Hall insulator with magnetic impurities. The resulting bound states hybridize and disperse along the edge, with discussions on the existence of zero-dimensional boundary modes. The construction is independent of impurity lattice details, and the stability of zero modes against disorder and random lattice configurations was confirmed numerically in a microscopic model.
Article
Materials Science, Multidisciplinary
T. Nathan Nunley, Side Guo, Liang-Juan Chang, David Lujan, Jeongheon Choe, Shang-Fan Lee, Fengyuan Yang, Xiaoqin Li
Summary: Recent research has found that thulium iron garnet (TmIG) based bilayers show promise in realizing small skyrmions at room temperature. By directly measuring the magnetic hysteresis loops, researchers have determined that the spin Hall topological Hall resistivity is considerably larger than previously estimated values. This finding further confirms the existence of skyrmions at room temperature and near-zero applied magnetic fields.
Article
Materials Science, Multidisciplinary
William P. Comaskey, Filippo Bodo, Alessandro Erba, Jose L. Mendoza-Cortes, Jacques K. Desmarais
Summary: The spin current density functional theory (SCDFT) is a generalization of standard DFT that is used to study fermionic systems with spin-orbit coupling. This study applies SCDFT to the quantum spin Hall phase and shows an improvement in the description of electronic features compared to DFT. The explicit consideration of spin currents in the electron-electron potential of SCDFT is found to be crucial for the appearance of the Dirac cone during the topological phase transition. Additionally, a simple k center dot p quasidegenerate perturbation theory model is used to rationalize the valence band structure of the system.
Article
Materials Science, Multidisciplinary
Qiang Cheng, Qing Yan, Qing-Feng Sun
Summary: Our study reveals that the Josephson effect in spin-triplet superconductor-quantum anomalous Hall insulator-spin-triplet superconductor junctions strongly depends on the orientations of the d vectors in superconductors, showing different effects for different configurations.
Article
Chemistry, Physical
Nguyen Ngoc Tri, Dai Q. Ho, A. J. P. Carvalho, Minh Tho Nguyen, Nguyen Tien Trung
Summary: Density functional theory calculations were used to investigate the intermolecular interactions between antibiotic molecules and the rutile-TiO2 surface, revealing that electrostatic interactions of TiO2 and hydrogen bonds play crucial roles in stabilizing the most favored structures. The existence and role of adsorptive interactions were clarified through atom-in-molecule theory, density of states, and electron density transfer analyses. The adsorption of antibiotic molecules on the r-TiO2 surface was characterized as chemisorption processes, with the most stable configurations forming in a horizontal arrangement.
Article
Materials Science, Multidisciplinary
Abhishek Sharan, Felipe Crasto de Lima, Shoaib Khalid, Roberto H. Miwa, Anderson Janotti
Summary: Using first-principles electronic structure calculations, it is shown that ferromagnetic Heusler compounds Co2MnX (X = Si, Ge, Sn) exhibit nontrivial topological characteristics and belong to the category of Weyl semimetals. These materials have two interesting band crossings near the Fermi level, characterized by topological features such as Hopf links and chain-like nodal lines protected by mirror planes.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2022)
Article
Materials Science, Multidisciplinary
D. Quang To, Zhengtianye Wang, Dai Q. Ho, Ruiqi Hu, Wilder Acuna, Yongchen Liu, Garnett W. Bryant, Anderson Janotti, Joshua M. O. Zide, Stephanie Law, Matthew F. Doty
Summary: We theoretically investigate the emergence of strong coupling in a system composed of a topological insulator (TI) and a III-V heterostructure. We find that the interaction between terahertz excitations in this structure creates new hybrid modes. Our results provide guidance for obtaining experimentally observable signatures of strong coupling by adjusting the material and device parameters.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Yongchen Liu, Wilder Acuna, Huairuo Zhang, Dai Q. Ho, Ruiqi Hu, Zhengtianye Wang, Anderson Janotti, Garnett Bryant, Albert V. Davydov, Joshua M. O. Zide, Stephanie Law
Summary: Terahertz technologies have broad applications and researchers are exploring the growth of Bi2Se3 on GaAs substrates as a step towards on-chip THz integrated systems. The study finds that achieving high-quality Bi2Se3 films requires an atomically smooth GaAs surface.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Tran Nam Trung, Nguyen Thi Thuy Kieu, Dai Q. Ho, Dong-Bum Seo, Eui-Tae Kim
Summary: In this study, Sn-doped TiO2 nanorods were synthesized and the doping mechanism of Sn into TiO2 was investigated. The experimental results verified the successful doping of Sn into TiO2, and the theoretical calculations explained how Sn substitutes for Ti in the crystal lattice and enhances the photocatalytic performance. The improved PEC performance of Sn-doped TiO2 nanorods suggests their potential as photocatalyst materials for solar energy-driven applications.
JOURNAL OF MATERIALS SCIENCE
(2023)
Article
Chemistry, Physical
Wei Li, Xue-Fen Cai, Nicholas Valdes, Tianshi Wang, William Shafarman, Su-Huai Wei, Anderson Janotti
Summary: This study reports the electronic and optical properties of γ-In2Se3 and Te-doped γ-In2(Se1-xTex)3 alloys using hybrid density functional theory calculations and initial experiments on γ-In2Se3 thin film growth and characterization. The experimental results are consistent with the calculated predictions and demonstrate that Te doping can tune the band gap range of the alloys, making them suitable for single-junction solar cells.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Intuon Chatratin, Baoying Dou, Su-Huai Wei, Anderson Janotti
Summary: Low p-type doping is a challenge for increasing the efficiency of CdTe thin-film solar cells. Previous calculations suggested high ionization energies for group-V acceptors, which resulted in self-compensation and limited hole concentration. However, recent experiments on CdTe single crystals showed that P, As, and Sb behave as shallow acceptors. Through hybrid functional calculations, it was found that the ionization energies decrease significantly with the supercell size. Including the effects of spin-orbit coupling and extrapolating to the dilute limit, it was determined that these impurities act as hydrogenic-like shallow acceptors, and AX centers do not limit p-type doping. Comparison with previous theoretical predictions and agreement with temperature-dependent Hall measurements were also discussed.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Hadass S. Inbar, Dai Q. Ho, Shouvik Chatterjee, Mihir Pendharkar, Aaron N. Engel, Jason T. Dong, Shoaib Khalid, Yu Hao Chang, Taozhi Guo, Alexei Fedorov, Donghui Lu, Makoto Hashimoto, Dan Read, Anderson Janotti, Christopher J. Palmstrom
Summary: This study investigates the electronic band structure and transport behavior of epitaxial GdSb thin films grown on III-V semiconductor surfaces. The GdSb thin films exhibit a hole-carrier rich, topologically trivial, semimetallic band structure. The carrier mobilities are limited by surface and interface scattering, resulting in lower magnetoresistance.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Physical
Intuon Chatratin, Baoying Dou, Su-Huai Wei, Anderson Janotti
Summary: Low p-type doping has been a barrier to achieving high efficiency in CdTe thin-film solar cells. Previous calculations predicted high ionization energies for group-V acceptors, leading to self-compensation and limited hole concentration. However, recent experiments on CdTe single crystals show that P, As, and Sb can behave as shallow acceptors. Using hybrid functional calculations, we demonstrate that the ionization energies decrease significantly with supercell size, and at the dilute limit, these impurities exhibit hydrogenic-like shallow acceptor behavior, eliminating the limitations of self-compensation.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Mateus B. P. Querne, Jean M. Bracht, Juarez L. F. Da Silva, Anderson Janotti, Matheus P. Lima
Summary: Two-dimensional semiconductor materials have the potential for unconventional applications, and their properties are still being explored. In this study, the researchers used ab initio simulations to investigate a class of emerging 2D materials, and found that one structure has higher stability and different optoelectronic properties compared to another structure.