Article
Materials Science, Multidisciplinary
Jie Chen, Xing Xu, Hang Li, Tengyu Guo, Bei Ding, Peng Chen, Hongwei Zhang, Xuekui Xi, Wenhong Wang
Summary: Controlling the anomalous Hall effect in magnetic topological materials is crucial, as observed in this study where the magnetic field influenced the anomalous Hall resistivity and the sign change in Weyl semimetal HoPtBi. Further analysis revealed that this effect originated from the field-induced shift of the Weyl points via exchange splitting of bands near the Fermi level, demonstrating a large tunable effect of the magnetic field on the electronic band structure.
Article
Materials Science, Multidisciplinary
Na Yang, Xiao-Ping Wei, Jing Shen, Xiaoma Tao
Summary: In this work, the researchers used first-principles calculations to predict the existence of multiple Weyl fermions and a large spin-down gap in 2D monolayer Cr2NT2. They observed chiral edge states and a quantum anomalous Hall effect when considering spin-orbit coupling. Additionally, they found that applying strain can lead to the emergence of rich topological phases. The researchers also constructed a tight-binding model to explain the origin of Weyl fermions in the non-trivial band topology.
MATERIALS CHEMISTRY AND PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Xiao-Ping Wei, Na Yang, Jing Shen, Xiaoma Tao
Summary: Using first-principles calculations, this study predicts that the 2D MXene Mn2NT2 exhibits half-metallic Weyl semimetal properties with rich topological phases and a quantum anomalous Hall effect. The research findings suggest that this material has potential applications in magnetoelectronic devices.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2022)
Article
Materials Science, Multidisciplinary
F. H. Yu, T. Wu, Z. Y. Wang, B. Lei, W. Z. Zhuo, J. J. Ying, X. H. Chen
Summary: A giant anomalous Hall effect (AHE) has been observed in kagome superconductor CsV3Sb5, with a conductivity reaching up to 2.1 x 10(4)Ω⁻¹ cm⁻¹, larger than most ferromagnetic metals. The emergence of AHE is strongly correlated with the higher-temperature charge-density-wave (CDW) transition, and AHE disappears when the CDW transition is completely suppressed under high pressure.
Article
Physics, Applied
Dongyao Zhang, Zhipeng Hou, Wenbo Mi
Summary: Researchers have fabricated Fe3Sn2 epitaxial films without buffer layers using the facing-target magnetron sputtering method and investigated their magneto-electronic transport properties. The sign of the Hall resistivity slope in a high-field region is reversed below 100 K, suggesting a temperature-induced transition of charge carriers. Additionally, a significant topological Hall resistivity has been observed.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Ekta Yadav, Sunil Kumar
Summary: Large size epitaxial thin films of ferromagnetic Co2MnGe full Heusler alloy were successfully grown over MgO(100) substrate using the pulsed laser deposition technique under optimized growth conditions. The films exhibited metallic behavior, with a minimum in resistivity observed at around 25 K due to disorder-induced weak localization effect. The epitaxial Co2MnGe film showed a dominating intrinsic anomalous Hall conductivity value of about 21 S cm(-1) at room temperature.
Article
Materials Science, Multidisciplinary
Yong-Chang Lau, Junya Ikeda, Kohei Fujiwara, Akihiro Ozawa, Jiaxin Zheng, Takeshi Seki, Kentaro Nomura, Liang Du, Quansheng Wu, Atsushi Tsukazaki, Koki Takanashi
Summary: Magnetic Weyl semimetals exhibit chiral Weyl node pairs and large intrinsic anomalous Hall effect. This study demonstrates the potential of Dirac nodes in paramagnetic state for efficient spin current generation at room temperature via the spin Hall effect.
Article
Materials Science, Multidisciplinary
Gaurav K. Shukla, Jyotirmoy Sau, Nisha Shahi, Anupam K. Singh, Manoranjan Kumar, Sanjay Singh
Summary: The study reveals that the Co2FeGe Heusler compound exhibits anomalous transport properties due to Weyl fermions and broken time-reversal symmetry. The experiment shows abnormal Hall conductivity at room temperature, with the main source being the Berry curvature originating from a gapped nodal line near the Fermi level.
Article
Chemistry, Physical
Weizhen Meng, Xiaoming Zhang, Weiwang Yu, Ying Liu, Lu Tian, Xuefang Dai, Guodong Liu
Summary: The prediction of a novel 2D topological material, monolayer EuO2, capable of realizing multiple types of topological states, particularly with 100% spin-polarization in Weyl points without considering spin-orbit coupling, promotes the realization of tunable topological phase in 2D half metals.
APPLIED SURFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Z. L. Sun, K. L. Peng, J. H. Cui, C. S. Zhu, W. Z. Zhuo, Z. Y. Wang, X. H. Chen
Summary: Pressure-dependent magnetotransport properties of GdPtBi were systematically studied, showing that AHC can be continuously tuned by applying hydrostatic pressure. The AHC decreases progressively with increasing pressure and eventually disappears at 1.5 GPa.
Article
Multidisciplinary Sciences
Daniel Kaplan, Tobias Holder, Binghai Yan
Summary: Can a generic magnetic insulator exhibit a Hall current? We find that a general magnetic insulator possesses a nonlinear Hall conductivity quadratic to the electric field if the system breaks inversion symmetry, which can be identified as a new type of multiferroic coupling. This conductivity originates from an induced orbital magnetization due to virtual interband transitions. In contrast to the crystalline solid, we find that this nonlinear Hall conductivity vanishes for Landau levels of a 2D electron gas, indicating a fundamental difference between the QAHE and the integer quantum Hall effect.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
T. Yokoi, S. Ma, Y. Kasahara, S. Kasahara, T. Shibauchi, N. Kurita, H. Tanaka, J. Nasu, Y. Motome, C. Hickey, S. Trebst, Y. Matsuda
Summary: Recent reports have shown the presence of half-integer thermal quantum Hall conductance in the two-dimensional honeycomb material alpha-RuCl3, even in magnetic fields without out-of-plane components. The measured field-angular variation of the quantized thermal Hall conductance in alpha-RuCl3 has the same sign structure as the topological Chern number of the pure Kitaev spin liquid, indicating that the non-Abelian topological order persists in the presence of non-Kitaev interactions.
Article
Physics, Applied
Yupeng Li, Jingang Zhou, Miaocong Li, Lei Qiao, Chenxi Jiang, Qiming Chen, Yuke Li, Qian Tao, Zhu-An Xu
Summary: This study demonstrates the significant enhancement of large anomalous Nernst effect (ANE) in magnetic topological materials (MTMs) with kagome lattice by tuning the Fermi level to Dirac nodal points.
PHYSICAL REVIEW APPLIED
(2023)
Article
Materials Science, Multidisciplinary
Yonatan Messica, Dmitri B. Gutman, Pavel M. Ostrovsky
Summary: We study the anomalous Hall effect in a disordered Weyl semimetal and show that the intrinsic contribution is expressed in terms of Berry curvature, while the extrinsic contribution is given by a combination of skewscattering and side-jump terms.
Article
Physics, Applied
Jie Chen, Peng Chen, Tengyu Guo, Dongfeng Zheng, Hang Li, Guoqiang Yu, Yong-Chang Lau, Xuekui Xi, Wenhong Wang
Summary: We conducted detailed magnetic and anisotropic magnetoresistance (AMR) measurements on a magnetic-field-induced topological Weyl semimetal, TbPtBi, which exhibits a weak metamagnetic transition in the antiferromagnetic state. The results indicate that the spin order dominates the symmetry of AMR curves at temperatures below the Neel temperature (T-N) and low magnetic fields. As the magnetic fields increase, the AMR with a twofold symmetry gradually becomes dominant. Moreover, sign change in the AMR effect is confirmed for both T < T-N and T > T-N at high magnetic fields, which may be related to the magnetic field-induced splitting of the topological band in TbPtBi.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Shiyu Fan, Sobhit Singh, Xianghan Xu, Kiman Park, Yubo Qi, S. W. Cheong, David Vanderbilt, Karin M. Rabe, J. L. Musfeldt
Summary: This study reports the vibrational properties of yttrium-stabilized HfO2 crystals and reveals the characteristic modes of polar orthorhombic hafnia by comparing the Raman and infrared spectra of different crystal phases. This research is of significance for analyzing the high-kappa dielectric and ferroelectric properties in chip technologies.
NPJ QUANTUM MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
K. Park, M. O. Yokosuk, M. Goryca, J. J. Yang, S. A. Crooker, S-W Cheong, K. Haule, D. Vanderbilt, H-S Kim, J. L. Musfeldt
Summary: In this study, by combining magneto-optical spectroscopy and first-principles calculations, we reveal the nonreciprocity and formation mechanism of Ni3TeO6 in the toroidal geometry. Additionally, we demonstrate the deterministic control of nonreciprocal directional dichroism in Ni3TeO6. These findings are of great significance for the development of photonics applications that utilize the unique symmetry characteristics of materials.
NPJ QUANTUM MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Sobhit Singh, Aldo H. Romero, Jose D. Mella, Vitalie Eremeev, Enrique Munoz, Anastassia N. Alexandrova, Karin M. Rabe, David Vanderbilt, Francisco Munoz
Summary: The two-dimensional material Mg2B4C2, belonging to the family of conventional superconductor MgB2, is predicted to exhibit high-temperature superconductivity without any external parameter tuning. The material's inert surfaces, large density of states, and strong electron-phonon coupling contribute to its high intrinsic critical temperature.
NPJ QUANTUM MATERIALS
(2022)
Article
Physics, Multidisciplinary
Wenbo Ge, Jinwoong Kim, Ying-Ting Chan, David Vanderbilt, Jiaqiang Yan, Weida Wu
Summary: We directly visualize the spin-flip transition of the surface layer in the antiferromagnet MnBi4Te7 using cryogenic magnetic force microscopy. Our observations confirm the presence of antiferromagnetic order in the surface layers. The magnetic field dependence of the images reveals a first-order spin-flip transition at a lower magnetic field than the bulk transition, matching a revised Mills model. This study provides insight into surface metamagnetic transitions in layered antiferromagnets and experimental support for quantized transport in ultrathin films of MnBi4Te7 and other natural superlattice topological magnets.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Subhasish Mandal, Kristjan Haule, Karin M. Rabe, David Vanderbilt
Summary: Systematic investigation using first principles calculations reveals that the computed bandwidths of nearly free-electron metals can be well described by the local approximation to the self-energy, providing a good agreement with angle-resolved photoemission experiments.
NPJ COMPUTATIONAL MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Yao-Wen Yeh, Sobhit Singh, Guangming Cheng, Nan Yao, Karin M. Rabe, David Vanderbilt, Philip E. Batson, Long Pan, Guofeng Xu, Shiyou Xu
Summary: In this study, the bonding state of calcium carbonate, a crucial building component in organisms, specifically the polymorphs calcite and aragonite, was characterized using valence (low-loss) electron energy loss spectroscopy. The difference in the Ca M23 edge, originating from 3p to 3d states, was found to align with the changes in Ca-O bonds in the two polymorphs. Surprisingly, the measured Ca M23 edge demonstrated qualitative agreement with the calculated partial density of states (PDOS) of Ca-d states, in contrast to the L edges (from 2p to 3d states) heavily influenced by atomic multiplet effect (spin-orbit coupling). These findings indicate that PDOS could potentially be utilized in interpreting the M23 edge of lighter 3d transition metals.
Article
Materials Science, Multidisciplinary
Daniel Seleznev, David Vanderbilt
Summary: The surface-normal component of the surface magnetization is investigated in a three-dimensional antiferromagnetic material. It is found that only crystals exhibiting pseudoscalar symmetry admit well-defined surface magnetizations. Multiple expressions for the quantum local marker are considered, and a particular form of the marker consistently predicts the correct macroscopic hinge currents.
Article
Materials Science, Multidisciplinary
Jinwoong Kim, Cheng-Yi Huang, Hsin Lin, David Vanderbilt, Nicholas Kioussis
Summary: The researchers propose that pristine bulk Bi can serve as a three-dimensional analog of the SSH model, demonstrating the existence of topologically nontrivial and trivial domain walls and providing criteria for determining the Zak phase of domain walls based on parity eigenvalues. They suggest that the dimerization reversal in Bi and the formation of domain walls can be achieved through intense femtosecond laser excitations.
Article
Materials Science, Multidisciplinary
Shang Ren, Hongbin Yang, Sobhit Singh, Philip E. Batson, Eric L. Garfunkel, David Vanderbilt
Summary: The electronic structure of Humble defects in Ge and Ge0.8Si0.2 is studied using first-principles calculations. Core-hole effects are found to be essential in reproducing the observed spectra. Humble defects are shown to enlarge the electronic band gap, and the use of hybrid functionals for a better description of the band gap is discussed.
Article
Materials Science, Multidisciplinary
Tanya Berry, Veronica J. Stewart, Benjamin W. Y. Redemann, Chris Lygouras, Nicodemos Varnava, David Vanderbilt, Tyrel M. McQueen
Summary: This study reports the synthesis and properties of the Zintl compound EuZn2P2 and its electronic structure calculations. The experimental results show that the compound exhibits insulating behavior and undergoes antiferromagnetic ordering at lower temperatures. The magnetic measurements indicate weak anisotropy and competing ferromagnetic and antiferromagnetic interactions. These findings are important for further predictive materials design.
Article
Materials Science, Multidisciplinary
Nicodemos Varnava, Tanya Berry, Tyrel M. McQueen, David Vanderbilt
Summary: Magnetic topological insulators provide an important material platform for quantum anomalous Hall physics and axion electrodynamics, but the lack of material realizations with cleanly gapped surfaces hinders their technological utilization. In this study, we computationally engineer magnetic topological insulators using the Zintl concept and the properties of nonsymmorphic space groups. We discover stable structures with nontrivial Z(2) indices in Eu5Ga2Sb6, Eu5Tl2Sb6, and Eu5In2Bi6 compounds. We also demonstrate that epitaxial and uniaxial strain can be used to control the Z(2) index and the bulk energy gap.
Article
Materials Science, Multidisciplinary
Minsung Kim, Heung-Sik Kim, Kristjan Haule, David Vanderbilt
Summary: This study theoretically investigates the phase transitions of layered metal phosphorous trisulfide FePS3 and finds that the Mott transition can be orbital selective. Under nonhydrostatic pressure, the t(2g) states undergo an insulator-metal transition while the e(g) states remain gapped. Increasing pressure further leads to crystal-field splitting and converts the system to a conventional Fermi liquid.
Article
Materials Science, Multidisciplinary
Sabine N. Neal, Sobhit Singh, Xiaochen Fang, Choongjae Won, Fei-ting Huang, Sang-Wook Cheong, Karin M. Rabe, David Vanderbilt, Janice L. Musfeldt
Summary: In this study, we investigated the properties of a two-sublattice ferroelectric material, CuInP2S6, by measuring its infrared and Raman scattering response across the ferroelectric and glassy transitions. Our findings, supported by symmetry analysis, phase stability calculations, and lattice dynamics, revealed the displacive character of the material, as well as the presence of two ferroelectric variants with opposite polarizations. We also observed a poorly understood relaxational or glassy transition below the ferroelectric transition temperature, characterized by subtle peak shifting and activation of low frequency modes.
Article
Materials Science, Multidisciplinary
Yuanyuan Xu, Huiyuan Man, Nan Tang, Takumi Ohtsuki, Santu Baidya, Satoru Nakatsuji, David Vanderbilt, Natalia Drichko
Summary: In this work, the coupling of lattice, electronic, and magnetic degrees of freedom in two pyrochlore materials, Pr2Zr2O7 and Pr2Ir2O7, is investigated. The comparison of Raman phonon spectra reveals the magnetoelastic coupling in Pr2Zr2O7 and characterizes the phonon-electron scattering in the semimetallic Pr2Ir2O7. The effects of random disorder on the Raman phonon spectra are found to be small.
Article
Materials Science, Multidisciplinary
Hongbin Yang, Shang Ren, Sobhit Singh, Emily M. Turner, Kevin S. Jones, Philip E. Batson, David Vanderbilt, Eric Garfunkel
Summary: A {001} planar defect was discovered in SiGe nanopillars, with the structure matching the Humble defect model proposed for diamond. The lowest energy variant of the Humble structure was found to be consistent with scanning transmission electron microscope images. The pillar composition was analyzed using electron energy loss spectroscopy, hinting at the formation process of the defect.