Article
Physics, Multidisciplinary
Yafei Ren, Cong Xiao, Daniyar Saparov, Qian Niu
Summary: The study investigates the adiabatic evolution of electronic states induced by the lattice vibration of a chiral phonon, obtaining electronic orbital magnetization in the form of a topological second Chern form. The traditional theory needs refinement by introducing a k-resolved Born effective charge and accounting for the phonon-modified electronic energy and momentum-space Berry curvature contribution. The second Chern form may diverge when a Yang's monopole is near the parameter space of interest, as demonstrated in a gapped graphene model at the Brillouin zone corner.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Yu-Hang Li, Ran Cheng
Summary: In magnetic topological insulators, quantized electronic transport is affected by magnetic ordering and magnetization controlling band gaps, and thermal spin fluctuations can significantly reduce the onset temperature of quantized transport even without structural impurities. This overlooked effect provides an alternative explanation for recent experiments on magnetic topological insulators.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Gero von Gersdorff, Shahram Panahiyan, Wei Chen
Summary: This article introduces a unified approach to obtain topological invariants in arbitrary dimensions and symmetry classes by introducing a wrapping number for topological materials described by Dirac models. This method is gauge-invariant, originates from the intrinsic features of the Dirac model, and places all known topological invariants on equal footing.
Article
Physics, Applied
Peng Liu, Hangyu Li, Zhitao Zhou, Yongmao Pei
Summary: This study provides experimental verification of pseudo-spin states on the boundary of an acoustic topological insulator using acoustic particle manipulation, revealing the characteristics of the pseudo-spin sound field and its potential application in controlling particle rotation.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
James H. H. Cullen, Rhonald Burgos Atencia, Dimitrie Culcer
Summary: Spin torques at topological insulator (TI)/ferromagnet interfaces have been studied to achieve electrical control of magnetic degrees of freedom. The relative contributions of bulk and surface states to spin torque are still not fully understood. In this study, the authors investigate the spin torques due to TI bulk states and find that there is no spin-orbit torque on a homogeneous magnetisation from the bulk states, unlike the surface states which give rise to a spin-orbit torque. The authors also discover a spin transfer torque due to the inhomogeneity of the magnetisation near the interface, which has not been considered before in TIs.
Article
Optics
Guochao Wei, Zhenzhen Liu, Licheng Wang, Jianyuan Song, Jun-Jun Xiao
Summary: This study demonstrates the existence of topological valley and pseudo-spin edge states in a carefully designed two-dimensional Kekule photonic crystal with time reversal symmetry. The presence of these edge states was confirmed through theoretical, numerical, and experimental analysis, and their distinct characteristics were identified through transmission measurements and end-scattering analysis.
PHOTONICS RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Hui Liu, Boyang Xie, Haonan Wang, Wenwei Liu, Zhancheng Li, Hua Cheng, Jianguo Tian, Zhengyou Liu, Shuqi Chen
Summary: Recent progress in studying topological Anderson insulators (TAIs) has shown that strong disorder can induce nontrivial topology from a trivial phase. In this study, a spin-Chern-type TAI was experimentally realized in a two-dimensional bilayer phononic crystal, and disorder-induced pseudospin-dependent helical boundary modes were observed. The robustness of these boundary modes was demonstrated, and the topological Anderson phase transition was confirmed by extending topological descriptions to disordered supercells and capturing the spin-Bott index. This work offers new perspectives for realizing interesting topological phases in optics, circuits, and cold atom systems.
Article
Physics, Multidisciplinary
B. Hafizi, D. Younis, D. F. Gordon
Summary: This paper investigates the spin characteristics of photoelectrons when hydrogen-like ions are centro-symmetrically irradiated with non-paraxial structured light. Photoelectrons with different helicities can be obtained, in contrast to the fixed helicities produced by left- or right-circularly polarized light. The angular distribution of photoelectrons is widely adjustable through radiation mode numbers.
NEW JOURNAL OF PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
A. V. Kapranov, R. S. Akzyanov, A. L. Rakhmanov
Summary: We study different types of vortices in a topological superconductor with nematic superconductivity in the Eu representation, including the Abrikosov vortex associated with vorticity in the particle-hole space and the spin vortex associated with vorticity in the spin space. By deriving the free energy using the Ginzburg-Landau approach, we calculate the critical strain at which the spin vortex is formed and show that the spin vortex and the Abrikosov vortex attract each other, resulting in a common core. We also apply Bogoliubov-de Gennes equations to study electronic states in a combined vortex structure and find no zero-energy states localized near the common vortex core of any type of vortex.
Article
Physics, Applied
Xiyin Ye, Hengyi Xu, Xiaoming Zhu
Summary: In this study, the thermoelectric effects of ferromagnetic topological insulators with two-dimensional circular or one-dimensional domain wall skyrmions are investigated. It is discovered that the topological spin textures play a crucial role in manipulating spin-dependent thermoelectric properties. Near the charge neutrality point, the spin Seebeck coefficients exhibit finite values that can be controlled by temperature, even though the charge Seebeck coefficients vanish. Circular skyrmions primarily affect edge-state transport regime by generating Fano antiresonances, while domain wall skyrmions influence the thermoelectric behaviors near the boundary between the edge-state and bulk-state transport regimes through resonant tunneling mechanism. Both types of skyrmions, with their effective functioning in distinct transport regimes, hold potential applications in thermoelectrics.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
K. Boboshko, A. Dyrdal, J. Barnas
Summary: The study examines bilinear magnetoresistance (BMR) and quadratic magnetoresistance (QMR) in systems with strong spin-orbit interaction, proposing a new mechanism based on scattering on spin-orbit impurities. Detailed characteristics of both BMR and QMR are presented and compared with results obtained for systems with spin-momentum locking inhomogeneities and hexagonal warping of the Dirac cones.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Federico Binda, Stefano Fedel, Santos Francisco Alvarado, Paul Noel, Pietro Gambardella
Summary: The study investigates the spin-orbit torques (SOTs) and spin Hall magnetoresistance generated by Bi0.9Sb0.1(0001) when coupled with FeCo, confirming its effectiveness as a spin-injector material. The research finds that charge-to-spin conversion in single-crystal Bi0.9Sb0.1(0001) is isotropic despite the strong anisotropy of the topological surface states. Additionally, the damping-like SOT displays non-monotonic temperature dependence, with a minimum occurring at 20 K.
ADVANCED MATERIALS
(2023)
Article
Optics
Xiang Zhou, Yiping Ding, Qinxin Yue, Shangling He, Yingji He, Dongmei Deng
Summary: The study investigates the tunable spin Hall effect of light on the surface of topological insulators under the influence of an external magnetic field, revealing that the shift of the effect is determined by the dissipative and reactive components of the insulators' optical conductivity. The shifts are insensitive to the magnetic field and Fermi energy at high frequencies but sensitive to them at low frequencies, with potential applications in determining these properties using the SHEL shifts.
OPTICS AND LASER TECHNOLOGY
(2022)
Article
Optics
[Anonymous]
Summary: The article introduces a type of topological defect found in electromagnetic waves, namely topological spin defects. Such defects are associated with points where the electromagnetic spin density is zero, and exhibit nontrivial topological spin textures and quantized topological charges. Examples of different types of defect points in electromagnetic fields are provided, with potential applications in 3D imaging and nanoparticle manipulation.
Article
Chemistry, Multidisciplinary
Polina M. Sheverdyaeva, Conor Hogan, Gustav Bihlmayer, Jun Fujii, Ivana Vobornik, Matteo Jugovac, Asish K. Kundu, Sandra Gardonio, Zipporah Rini Benher, Giovanni Di Santo, Sara Gonzalez, Luca Petaccia, Carlo Carbone, Paolo Moras
Summary: Topological insulators are bulk insulators with metallic and fully spin-polarized surface states exhibiting Dirac-like band dispersion. By using spin-resolved photoemission spectroscopy, we show that the topological surface states of a topological insulator interfaced with an antimonene bilayer exhibit nearly full out-of-plane spin polarization within the substrate gap. This phenomenon is connected to a symmetry-protected band crossing of the spin-polarized surface states. The nearly full out-of-plane spin polarization of the topological surface states occurs along a continuous path in the energy-momentum space, and the spin polarization within the gap can be reversibly tuned from nearly full out-of-plane to nearly full in-plane by electron doping. These findings pave the way for advanced spintronics applications that exploit the giant out-of-plane spin polarization of topological surface states.
Article
Multidisciplinary Sciences
Kangwon Kim, Soo Yeon Lim, Jae-Ung Lee, Sungmin Lee, Tae Yun Kim, Kisoo Park, Gun Sang Jeon, Cheol-Hwan Park, Je-Geun Park, Hyeonsik Cheong
NATURE COMMUNICATIONS
(2019)
Article
Materials Science, Multidisciplinary
Kangwon Kim, Soo Yeon Lim, Jungcheol Kim, Jae-Ung Lee, Sungmin Lee, Pilkwang Kim, Kisoo Park, Suhan Son, Cheol-Hwan Park, Je-Geun Park, Hyeonsik Cheong
Article
Multidisciplinary Sciences
Seunghyun Park, Soonmin Kang, Haeri Kim, Ki Hoon Lee, Pilkwang Kim, Sangwoo Sim, Nahyun Lee, Balamurugan Karuppannan, Junghyun Kim, Jonghyeon Kim, Kyung Ik Sim, Matthew J. Coak, Yukio Noda, Cheol-Hwan Park, Jae Hoon Kim, Je-Geun Park
SCIENTIFIC REPORTS
(2020)
Article
Chemistry, Physical
Seung-Ju Hong, Jae-Mo Lihm, Cheol-Hwan Park
Summary: Using T-matrix theory, this study shows that the assumption of independence of quasiparticle interference patterns in momentum space with the strength of the impurity potential breaks down. A rich, impurity-strength-dependent structure in the QPI pattern of TaAs is predicted, emphasizing the importance of considering the details of the scattering impurity in interpreting Fourier-transform scanning tunneling spectroscopy experiments.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Tae Yun Kim, Cheol-Hwan Park
Summary: A magnetic model with a large number of parameters was determined from first-principles calculations for transition-metal phosphorus trisulfides, successfully reproducing the measured magnetic ground states. The results show that the antiferromagnetic order persists down to monolayers, and the orbital polarization dramatically enhances the magnetic anisotropy of FePS3.
Article
Physics, Multidisciplinary
Jae-Mo Lihm, Cheol-Hwan Park
Summary: Wannier function perturbation theory is a versatile method that can be readily applied to calculate a wide range of quantities related to various kinds of perturbations.
Correction
Physics, Multidisciplinary
Jae-Mo Lihm, Cheol-Hwan Park
Article
Materials Science, Multidisciplinary
Minsu Ghim, Cheol-Hwan Park
Summary: This paper introduces a tetrahedron method for k-space summation in solid-state physics, which includes the energy-conserving delta-function part and the nondissipative part. The paper presents a stable method to overcome technical difficulties in the tetrahedron method for the nondissipative part and demonstrates its effectiveness by calculating the spin Hall conductivity of platinum. The method can be widely applied to calculate linear static or dynamical conductivity, spin Hall conductivity, self-energy of an electron, and electric polarizability.
Article
Materials Science, Multidisciplinary
Yang-Jun Lee, Cheol-Hwan Park, Maria A. H. Vozmediano
Summary: The collapse of Landau levels induced by strain in anisotropic, tilted Weyl semimetals is analyzed, and the conditions for experimentally accessible external strain in TaAs are determined through first-principles calculations.
Article
Materials Science, Multidisciplinary
Jae-Mo Lihm, Cheol-Hwan Park
Summary: A general theory of second-order spin photocurrents applicable to real materials with spin-orbit coupling or noncollinear magnetism has been developed, and the phenomenon of pure spin rectification current has been predicted in an insulator induced by subgap light with energies lower than the material band gap.
Article
Physics, Multidisciplinary
Jae-Mo Lihm, Cheol-Hwan Park
Summary: The self-consistent harmonic approximation is proven useful for studying the equilibrium properties of anharmonic lattices, but the study of dynamical properties still requires further exploration. By applying the time-dependent variational principle, an analytical formula for position-position correlation function and phonon self-energy in anharmonic lattice is derived, confirming the dynamical ansatz of the self-consistent harmonic approximation. This work establishes a fruitful connection between the time-dependent variational principle and anharmonic lattice Hamiltonian, providing insights in both fields.
PHYSICAL REVIEW RESEARCH
(2021)
Article
Materials Science, Multidisciplinary
Hanyoung Ryu, Jae-Mo Lihm, Joonil Cha, Beomyoung Kim, Beom Seo Kim, Wonshik Kyung, Inkyung Song, Yeongkwan Kim, Garam Han, Jonathan Denlinger, In Chung, Cheol-Hwan Park, Seung Ryong Park, Changyoung Kim
Summary: By conducting angle-resolved photoemission studies on ferroelectric alpha-GeTe(111), it was observed that the Rashba splitting size of surface states is reduced upon potassium (K) doping, due to a decrease in surface potential energy barrier. This change in surface potential leads to delocalization of the surface states and reduction of the splitting size, suggesting the potential to increase the splitting size by doping other elements or molecules with high electron affinity.
Article
Materials Science, Multidisciplinary
Jae-Mo Lihm, Cheol-Hwan Park
Article
Materials Science, Multidisciplinary
Ji Hoon Ryoo, Cheol-Hwan Park, Ivo Souza
Article
Materials Science, Multidisciplinary
Jae-Mo Lihm, Cheol-Hwan Park
