Article
Chemistry, Multidisciplinary
Jinjun Ding, Chuanpu Liu, Vijaysankar Kalappattil, Yuejie Zhang, Oleksandr Mosendz, Uppalaiah Erugu, Rui Yu, Jifa Tian, August DeMann, Stuart B. Field, Xiaofei Yang, Haifeng Ding, Jinke Tang, Bruce Terris, Albert Fert, Hua Chen, Mingzhong Wu
Summary: Recent experiments have shown that topological surface states (TSS) in a topological Dirac semimetal α-Sn can induce current-induced magnetization switching in ferromagnets without the need for an external magnetic field, demonstrating similar efficiency to topological insulators (TI) systems.
ADVANCED MATERIALS
(2021)
Article
Multidisciplinary Sciences
Masataka Mogi, Kenji Yasuda, Reika Fujimura, Ryutaro Yoshimi, Naoki Ogawa, Atsushi Tsukazaki, Minoru Kawamura, Kei S. Takahashi, Masashi Kawasaki, Yoshinori Tokura
Summary: Efficient current-induced switching of surface ferromagnetism in hetero-bilayers of topological insulator (Bi1-xSbx)(2)Te-3 and ferromagnetic insulator Cr2Ge2Te6 demonstrates the potential for electrical control of dissipationless topological-current circuits, showing efficient charge-to-spin current conversion and large anomalous Hall effect.
NATURE COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Wenjun Kuang, Guillermo Lopez-Polin, Hyungjun Lee, Francisco Guinea, George Whitehead, Ivan Timokhin, Alexey Berdyugin, Roshan Krishna Kumar, Oleg Yazyev, Niels Walet, Alessandro Principi, Andre K. Geim, Irina Grigorieva
Summary: Superconductors with nontrivial band structure topology have unique properties and are difficult to distinguish due to dominant contributions from superconducting bulk. Anomalous behavior of surface superconductivity in a topologically nontrivial 3D superconductor, In2Bi, has been reported, showcasing the potential for macroscopic magnetization as a new tool for the discovery and identification of topological superconductors.
ADVANCED MATERIALS
(2021)
Article
Multidisciplinary Sciences
Rui Su, Sanjib Ghosh, Timothy C. H. Liew, Qihua Xiong
Summary: The research demonstrated a room temperature exciton polariton topological insulator and proved that polarization can be used as a degree of freedom to switch between different topological phases, showing strong immunity to perturbations. The study also showed that exciton polaritons can condense into topological edge states under optical pumping, providing an ideal platform for active topological polaritonic devices operating under ambient conditions.
Article
Multidisciplinary Sciences
Daniel Rosenbach, Tobias W. Schmitt, Peter Schueffelgen, Martin P. Stehno, Chuan Li, Michael Schleenvoigt, Abdur R. Jalil, Gregor Mussler, Elmar Neumann, Stefan Trellenkamp, Alexander A. Golubov, Alexander Brinkman, Detlev Gruetzmacher, Thomas Schaepers
Summary: The article discusses the discovery of a 4 pi periodic current phase relation in Josephson junctions with topological weak links and the attenuation and quantization phenomena observed in certain structures.
Article
Multidisciplinary Sciences
C. P. Schmid, L. Weigl, P. Groessing, V Junk, C. Gorini, S. Schlauderer, S. Ito, M. Meierhofer, N. Hofmann, D. Afanasiev, J. Crewse, K. A. Kokh, O. E. Tereshchenko, J. Guedde, F. Evers, J. Wilhelm, K. Richter, U. Hoefer, R. Huber
Summary: This study experimentally demonstrates high-order harmonic generation in a three-dimensional topological insulator, bismuth telluride. By using a specific frequency of the driving field, the generation of high-order harmonics from the bulk and topological surface was successfully differentiated, revealing unconventional HH generation processes.
Review
Physics, Applied
Oliver Breunig, Yoichi Ando
Summary: Topological insulators are unique materials that result in unconventional quantum phenomena. To observe these phenomena experimentally, sophisticated devices are required. This Technical Review discusses various physics effects that can be observed in carefully fabricated devices, including topological superconductivity, quantum anomalous Hall states, spintronic functionalities and topological mesoscopic physics.
NATURE REVIEWS PHYSICS
(2022)
Article
Multidisciplinary Sciences
Haiyu Wang, Hao Wu, Jie Zhang, Yingjie Liu, Dongdong Chen, Chandan Pandey, Jialiang Yin, Dahai Wei, Na Lei, Shuyuan Shi, Haichang Lu, Peng Li, Albert Fert, Kang L. Wang, Tianxiao Nie, Weisheng Zhao
Summary: In this study, we demonstrate room-temperature spin-orbit torque driven magnetization switching in an all-van der Waals heterostructure using an optimized epitaxial growth approach. By utilizing the topological insulator Bi2Te3 as a spin current source, we are able to achieve switching at a low current density and raise the Curie temperature of Fe3GeTe2.
NATURE COMMUNICATIONS
(2023)
Article
Optics
Yin Huang, Yuecheng Shen, Georgios Veronis
Summary: We introduce a non-Hermitian plasmonic waveguide-cavity structure based on the Aubry-Andre-Harper model, which allows for switching between right and left topological edge states (TESs). By utilizing the phase-change material GST, we demonstrate that switching between the crystalline and amorphous phases enables the occurrence of right TES in the crystalline phase and left TES in the amorphous phase at the same frequency. This work has the potential to contribute to the development of compact and reconfigurable topological photonic devices.
Article
Nanoscience & Nanotechnology
Antonina A. Arkhipova, Sergey K. Ivanov, Sergey A. Zhuravitskii, Nikolay N. Skryabin, Ivan Dyakonov, Alexander A. Kalinkin, Sergey P. Kulik, Victor O. Kompanets, Sergey Chekalin, Yaroslav Kartashov, Victor N. Zadkov
Summary: We report the experimental observation of periodic switching of topological edge states in dimerized fs-laser written waveguide arrays. The switching can be controlled and even completely arrested by adjusting the spacing between the arrays and the input signal power. When the topological arrays come in contact with non-topological ones, either the formation of nearly stationary topological interface mode or strongly asymmetric diffraction into the non-topological array is observed depending on the initial excitation position.
Article
Multidisciplinary Sciences
David A. Kealhofer, Robert Kealhofer, Daniel Ohara, Tyler N. Pardue, Susanne Stemmer
Summary: A thin film of cadmium arsenide can exhibit the characteristics of a three-dimensional topological insulator, with experimental signatures observed through quantum capacitance. By leveraging the flexibility of heterostructures, researchers have demonstrated a method to control the energy of topological surface states in cadmium arsenide, opening up new avenues for engineering topological insulators based on this material.
Article
Chemistry, Multidisciplinary
Kaixuan Zhang, Youjin Lee, Matthew J. Coak, Junghyun Kim, Suhan Son, Inho Hwang, Dong-Su Ko, Youngtek Oh, Insu Jeon, Dohun Kim, Changgan Zeng, Hyun-Woo Lee, Je-Geun Park
Summary: This research successfully demonstrates a multi-level spin memory using van-der-Waals (vdW) topological ferromagnet Fe3GeTe2, achieving nonvolatile and highly energy-efficient magnetization switching. The ability to control magnetic information with a tiny current and switch multiple states electrically shows great potential for enhancing information capacity density and reducing computing costs in spintronics.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Multidisciplinary Sciences
Sangmo Cheon, Ki Hoon Lee, Suk Bum Chung, Bohm-Jung Yang
Summary: This study reports unconventional superconductivity in doped topological DSM, discusses the effects of lattice distortion on unconventional superconductivity, identifies four types of symmetry-lowering lattice distortions through theoretical analysis, and calculates possible superconducting phase diagrams. The results suggest that lattice distortions can induce unconventional superconductivity with gapless surface Andreev bound states (SABS), and the critical temperature of superconductivity increases with lattice distortions, in line with experimental observations.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Multidisciplinary
Maxime Verges, Sreekanth Perumbilavil, Julius Hohlfeld, Francisco Freire-Fernandez, Yann Le Guen, Nikolai Kuznetsov, Francois Montaigne, Gregory Malinowski, Daniel Lacour, Michel Hehn, Sebastiaan van Dijken, Stephane Mangin
Summary: The impact of plasmonic surface lattice resonances on the magneto-optical properties and energy absorption efficiency of [Co/Gd/Pt](N) multilayer nanodisks has been investigated. It is shown that surface lattice resonances enable all-optical single pulse switching of [Co/Gd/Pt](N) nanodisk arrays with 400% lower energy than continuous [Co/Gd/Pt](N) films. Additionally, the magneto-optical Faraday effect is enhanced by up to 5,000% at resonance condition. The study demonstrates the potential for designing magnetic metasurfaces for all-optical magnetization switching applications.
Article
Chemistry, Physical
I-Hsuan Kao, Ryan Muzzio, Hantao Zhang, Menglin Zhu, Jacob Gobbo, Sean Yuan, Daniel Weber, Rahul Rao, Jiahan Li, James H. Edgar, Joshua E. Goldberger, Jiaqiang Yan, David G. Mandrus, Jinwoo Hwang, Ran Cheng, Jyoti Katoch, Simranjeet Singh
Summary: This paper demonstrates the experimental realization of field-free deterministic magnetic switching using the out-of-plane antidamping spin-orbit torque in the quantum material WTe2, and confirms this phenomenon through numerical simulations. This is of great importance for next-generation spintronic applications.
Article
Chemistry, Multidisciplinary
Ruofan Li, Peng Li, Di Yi, Lauren J. Riddiford, Yahong Chai, Yuri Suzuki, Daniel C. Ralph, Tianxiang Nan
Summary: Magnon-mediated spin flow in magnetically ordered insulators enables long-distance spin-based information transport with low dissipation. In this study, anisotropy in magnon spin transport was observed in spinel ferrite, providing an approach for controlling magnonic devices via strain.
Article
Engineering, Electrical & Electronic
Chunli Tang, Laith Alahmed, Jihao Xu, Maokang Shen, Nicholas Alex Jones, Mehdi Sadi, Ujjwal Guin, Wenfeng Zhao, Peng Li
Summary: A skyrmion-magnetic domain interconversion logic gate (SkyMDILogic) was designed as a model system to investigate the effects of temperature and structural defects. Micromagnetic simulations and an equivalent circuit model were used to study skyrmion movement and energy consumption at different temperatures. The study found that temperature significantly influences the stability and propagation of skyrmions, highlighting the importance of thermal and structural defect effects in logic gate designs.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Physics, Applied
Robin Klause, Axel Hoffmann
Summary: Materials with large spin-orbit interactions can generate pure spin currents with spin polarizations parallel to the interfacial surfaces, resulting in conventional spin-orbit torques. Non-collinear antiferromagnets can break additional symmetry and generate exotic spin-orbit torques with spin polarizations perpendicular to the interfacial planes. Through micromagnetic simulations, it has been found that these exotic spin-orbit torques can generate magnetic droplet solitions in out-of-plane magnetized geometries.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Martin Lonsky, Axel Hoffmann
Summary: This study presents comprehensive micromagnetic simulations of Synthetic antiferromagnet (SAF) nanostructures with an interfacial Dzyaloshinskii-Moriya interaction, discussing rich phase diagrams with various magnetic configurations, resonant excitations of individual skyrmions and skyrmioniums, and the internal modes of SAF skyrmion clusters in the context of magnetic sensing applications.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
Ilkin Goksal, Hasan Piskin, Bayram Kocaman, Kutay Akin, Dogukan Cay, Ege Selvi, Vedat Karakas, Sergi Lendinez, Hilal Saglam, Yi Li, John E. Pearson, Ralu Divan, Wei Zhang, Valentine Novosad, Axel Hoffmann, Ozhan Ozatay
Summary: This study investigates the conditions under which an ultra-thin metallic antiferromagnet becomes susceptible to spin-orbit torques. The results indicate that there is a specific range of thickness where the spins can be controlled by spin-orbit torques, while lower and higher thicknesses affect the sensitivity to spin currents. Structural changes in multilayers also quench local torques.
INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS
(2023)
Article
Chemistry, Multidisciplinary
Run Xiao, Saurav Islam, Wilson Yanez, Yongxi Ou, Haiwen Liu, Xincheng Xie, Juan Chamorro, Tyrel M. McQueen, Nitin Samarth
Summary: Time-reversal invariance and inversion symmetry are responsible for the topological band structure in Dirac semimetals. Applying an external magnetic or electric field can break these symmetries and cause fundamental changes to the ground state Hamiltonian and a topological phase transition. We use universal conductance fluctuations in Cd3As2 to probe these changes. The magnitude of the fluctuations decreases with increasing magnetic field, consistent with the effect of broken time-reversal invariance. However, the magnitude increases monotonically when the chemical potential is gated away from the charge neutrality point, attributed to Fermi surface anisotropy rather than broken inversion symmetry. The agreement between experimental data and theory provides unequivocal evidence that universal conductance fluctuations are the dominant source of fluctuations and offers a general methodology for probing broken-symmetry effects in topological quantum materials.
Article
Multidisciplinary Sciences
Hangtian Wang, Haichang Lu, Zongxia Guo, Ang Li, Peichen Wu, Jing Li, Weiran Xie, Zhimei Sun, Peng Li, Heloise Damas, Anna Maria Friedel, Sylvie Migot, Jaafar Ghanbaja, Luc Moreau, Yannick Fagot-Revurat, Sebastien Petit-Watelot, Thomas Hauet, John Robertson, Stephane Mangin, Weisheng Zhao, Tianxiao Nie
Summary: In this study, a large-scale iron-based vdW material Fe4GeTe2 with a high Curie temperature (Tc) of around 530 K was developed and its high-temperature ferromagnetism was confirmed by multiple characterizations. Theoretical calculations indicated that the interface-induced right shift of unpaired Fe d electrons' localized states is responsible for the enhanced Tc, which was confirmed by ultraviolet photoelectron spectroscopy. Additionally, by precisely tailoring Fe concentration, arbitrary control of magnetic anisotropy between out-of-plane and in-plane was achieved without inducing any phase disorders. This finding highlights the high potential of Fe4GeTe2 in spintronics, potentially enabling the room-temperature application of all-vdW spintronic devices.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Applied
Peng Li, Sanyum Channa, Xiang Li, Laith Alahmed, Chunli Tang, Di Yi, Lauren Riddiford, Jacob Wisser, Purnima P. Balakrishnan, Xin Yu Zheng, Di Lu, Arturas Vailionis, Shan X. Wang, Yuri Suzuki
Summary: We demonstrate energy-efficient room-temperature spin-orbit-torque (SOT) switching in nanometer-thick CoFeB/SrIrO3 bilayers, despite the amorphous nature of CoFeB and the interface. The large spin Hall angle in SrIrO3 and the high spin transmission at the interface contribute to the SOT efficiency. Our bilayers exhibit significant SOT and effective spin Hall conductivity, as well as low critical current density for current-induced magnetization switching at room temperature. Our results show promise for heterostructures combining CoFeB with high spin-orbit-coupling oxides.
PHYSICAL REVIEW APPLIED
(2023)
Article
Nanoscience & Nanotechnology
Qianwen Zhao, ChaoChao Xia, Hanying Zhang, Baiqing Jiang, Tunan Xie, Kaihua Lou, Chong Bi
Summary: The discovery of ferromagnetism in 2D monolayers has sparked interest in spintronics and material science. However, large-scale fabrication and the correlation between ferromagnetism and crystalline order remain unresolved. This study investigates the ferromagnetism of Fe3GeTe2 in an amorphous state and finds that the basic ferromagnetic attributes remain unchanged. This suggests that the long-range ferromagnetic order of crystallized Fe3GeTe2 may not be correlated to the 2D crystalline order and could have applications in spintronics fabrication.
ACS APPLIED NANO MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Qianwen Zhao, Yingmei Zhu, Hanying Zhang, Baiqing Jiang, Yuan Wang, Tunan Xie, Kaihua Lou, Chaochao Xia, Hongxin Yang, Chong Bi
Summary: Researchers induced room-temperature ferromagnetism using magnetic proximity effect at the interface between Pt and Fe3GeTe2, providing a new approach for creating room-temperature functional spin devices based on low-Tc materials, and offering clear evidence of magnetic proximity effects.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Physics, Applied
Yi Li, Tzu-Hsiang Lo, Jinho Lim, John E. Pearson, Ralu Divan, Wei Zhang, Ulrich Welp, Wai-Kwong Kwok, Axel Hoffmann, Valentine Novosad
Summary: Researchers achieve unidirectional microwave transduction with sub-micrometer-wavelength propagating magnons in a yttrium iron garnet (YIG) thin-film delay line, obtaining non-decaying isolation of 30 dB and a broad field-tunable bandpass frequency range up to 14 GHz.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
G. Wang, P. S. S. Barry, T. Cecil, C. L. L. Chang, J. Li, M. Lisovenko, V Novosad, Z. Pan, V. G. G. Yefremenko, J. Zhang
Summary: The complex conductivity of a superconducting thin film is influenced by the quasiparticle density, which can be altered by external interventions such as photons and phonons. This property is applied in Kinetic Inductance Detectors (KIDs) to determine the detection threshold. In this study, we explore the electromagnetic properties of aluminum thin films proximitized with copper or lower T-C superconducting layers (such as iridium) to enhance the operating range of KIDs. By utilizing the Usadel equations and Nam expressions, we calculate the density of states and complex conductivity of bilayers, providing insights into the pair breaking threshold, surface impedance, and intrinsic quality factor.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Engineering, Electrical & Electronic
M. Lisovenko, Z. Pan, P. S. Barry, T. Cecil, C. L. Chang, K. R. Dibert, R. Gualtieri, J. Li, V. Novosad, G. Wang, V. Yefremenko
Summary: Silicon-based dielectric is crucial for superconducting devices, and defects and contaminants can degrade device performance. The fabrication and characterization of silicon oxide and nitride thin film dielectrics were conducted using various deposition methods. The resulting films were used in superconducting resonant systems, and their properties were measured.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Materials Science, Multidisciplinary
Fan Zhang, Asmaul Smitha Rashid, Mostafa Tanhayi Ahari, Wei Zhang, Krishnan Mekkanamkulam Ananthanarayanan, Run Xiao, George J. de Coster, Matthew J. Gilbert, Nitin Samarth, Morteza Kayyalha
Summary: There is a growing interest in using multiterminal Josephson junctions to emulate topological phases and investigate superconducting mechanisms. However, the interpretation of experimental signatures in MTJJs has been conflicting. In this study, graphene-based four-terminal Josephson junctions were investigated experimentally and theoretically. Resonant features in the differential resistance maps were observed and successfully reproduced using a circuit network model. The study suggests that differential resistance measurements alone cannot distinguish resonant Andreev reflection processes from semiclassical circuit-network effects.
