Unconventional Planar Hall Effect in Exchange-Coupled Topological Insulator-Ferromagnetic Insulator Heterostructures

Abstract

The Dirac electrons occupying the surface states (SSs) of topological insulators (TIs) have been predicted to exhibit many exciting magneto-transport phenomena. Here we report on the first experimental observation of an unconventional planar Hall effect (PHE) and an electrically gate-tunable hysteretic planar magnetoresistance (PMR) in EuS/TI heterostructures, in which EuS is a ferromagnetic insulator (FMI) with an in-plane magnetization. In such exchange-coupled FMI/TI heterostructures, we find a significant (suppressed) PHE when the in-plane magnetic field is parallel (perpendicular) to the electric current. This behavior differs from previous observations of the PHE in ferromagnets and semiconductors. Furthermore, as the thickness of the 3D TI films is reduced into the 2D limit, in which the Dirac SSs develop a hybridization gap, we find a suppression of the PHE around the charge neutral point indicating the vital role of Dirac SSs in this phenomenon. To explain our findings, we outline a symmetry argument that excludes linear-Hall mechanisms and suggest two possible non-linear Hall mechanisms that can account for all the essential qualitative features in our observations.

17 pages, 4 figures, accepted by Phys. Rev. B

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• Theory of spin Hall magnetoresistance
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Cited by in corpus (15)

• Planar Hall Effect and Anisotropic Magnetoresistance in a polar-polar interface of LaVO${}_3$-KTaO${}_3$ with strong spin-orbit coupling
• Intrinsic Nonlinear Planar Hall Effect
• Progress and prospects in the quantum anomalous Hall effect
• Evidence for exchange Dirac gap in magneto-transport of topological insulator-magnetic insulator heterostructures
• Observation of Planar Hall Effect in Topological Insulator -- Bi${}_2$Te${}_3$
• Signatures of long-range-correlated disorder in the magnetotransport of ultrathin topological insulators
• Observation of nonlinear planar Hall effect in magnetic insulator/topological insulator heterostructures
• Spectral features of magnetic domain walls on surface of 3D topological insulators
• Hexagonal Warping Induced Nonlinear Planar Nernst Effect in Nonmagnetic Topological Insulators
• Planar Hall Effect in Quasi-Two-Dimensional Materials
• Finite transverse conductance in topological insulators under an applied in-plane magnetic field
• Finite transverse conductance and anisotropic magnetoconductance under an applied in-plane magnetic field in two-dimensional electron gases with strong spin-orbit coupling
• Quantum oscillations of the nonlinear planar effects signifying chiral anomaly in Weyl Semimetals
• Anisotropic planar Hall effects in Bi${}_2$Se${}_3$/EuS interfaces: Deciphering the role of proximity induced spin canting and topological spin texture
• Super-resonant transport of topological surface states subjected to in-plane magnetic fields