A new mechanism of bilinear magnetoresistance (BMR) is proposed and studied theoretically within the minimal model describing surface electronic states in topological insulators. The BMR appears as a consequence of the second-order response to electric field, and depends linearly on both magnetic field and current (electric field). The mechanism is based on the interplay of current-induced spin polarization and scattering processes due to inhomogeneities of spin-momentum locking, that unavoidably appear as a result of structural defects in topological insulators. The proposed mechanism leads to the BMR even if the electronic band structure is isotropic (e.g., absence of hexagonal warping), and is shown to be dominant at lower Fermi energies.
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http://dx.doi.org/10.1103/PhysRevLett.124.046802 | DOI Listing |
Nat Mater
January 2025
Max Planck Institute for Chemical Physics of Solids, Dresden, Germany.
High thermoelectric performance is generally achieved by synergistically optimizing two or even three of the contradictorily coupled thermoelectric parameters. Here we demonstrate magneto-thermoelectric correlation as a strategy to achieve simultaneous gain in an enhanced Seebeck coefficient and reduced thermal conductivity in topological materials. We report a large magneto-Seebeck effect and high magneto-thermoelectric figure of merit of 1.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
School of Physics, Beihang University, Haidian District, Beijing 100191, China.
Massive Dirac fermions, which are essential for realizing novel topological phenomena, are expected to be generated from massless Dirac fermions by breaking the related symmetry, such as time-reversal symmetry in topological insulators or crystal symmetry in topological crystalline insulators. Here, we report scanning tunneling microscopy and angle-resolved photoemission spectroscopy studies of α-Bi_{4}I_{4}, which reveals the realization of massive Dirac fermions in the (100) surface states without breaking the time-reversal symmetry. Combined with first-principles calculations, our experimental results indicate that the spontaneous symmetry breaking engenders two nondegenerate edge states at the opposite sides of monolayer Bi_{4}I_{4} after the structural phase transition, imparting mass to the Dirac fermions after taking the interlayer coupling into account.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Key Laboratory of Materials Physics of Ministry of Education, School of Physics, Zhengzhou University, Zhengzhou 450001, China.
Manipulating elastic waves in lower-dimensional mechanical metamaterials has attracted much attention since it lays the foundation for the design of various elastic functional devices, especially for on-chip size. However, due to the experimental challenges, it is very difficult to control elastic waves in higher dimensions. In this Letter, we introduce an extra structural parameter to synthesize and investigate the on-chip Weyl physics in silicon-on-insulator system.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA.
The topological magnetoelectric effect (TME) is a defining property of three-dimensional Z_{2} topological insulators that was predicted on theoretical grounds more than a decade ago, but has still not been directly measured. In this Letter we propose a strategy for direct measurement of the TME and discuss the precision of the effect in real devices with charge and spin disorder.
View Article and Find Full Text PDFMater Horiz
January 2025
Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, 2500, Australia.
Recently, the emergence of two-dimensional (2D) multiferroic materials has opened a new perspective for exploring topological states. However, instances of tuning topological phase transitions through ferroelectric (FE) polarization in 2D ferromagnetic (FM) materials are relatively rare. Here, we found that 11 single layer (SL) materials, named the MMGeX family, possess both FE and FM properties.
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