Coexistence of surface and bulk ferromagnetism mimics skyrmion Hall effect in a topological insulator

Abstract

Here we report the investigation of the anomalous Hall effect in the magnetically doped topological insulator (V,Bi,Sb)2Te3. We find it contains two contributions of opposite sign. Both components are found to depend differently on carrier density, leading to a sign inversion of the total anomalous Hall effect as a function of applied gate voltage. The two contributions are found to have different magnetization reversal fields, which in combination with a temperature dependent study points towards the coexistence of two ferromagnetic orders in the system. Moreover, we find that the sign of total anomalous Hall response of the system depends on the thickness and magnetic doping density of the magnetic layer. The thickness dependence suggests that the two ferromagnetic components originate from the surface and bulk of the magnetic topological insulator film. We believe that our observations provide insight on the magnetic behavior, and thus will contribute to an eventual understanding of the origin of magnetism in this material class. In addition, our data bears a striking resemblance to anomalous Hall signals often associated with skyrmion contributions. Our analysis provides a straightforward explanation for both the magnetic field dependence of the Hall signal and the observed change in sign without needing to invoke skyrmions, and thus suggest that caution is needed when making claims of effects from skyrmion phases.

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Cited by in corpus (9)

• Even-Odd Layer-Dependent Anomalous Hall Effect in Topological Magnet MnBi2Te4 Thin Films
• Giant Topological Hall Effect in van der Waals Heterostructures of CrTe2/Bi2Te3
• Distinguishing two-component anomalous Hall effect from topological Hall effect
• Topological Hall Effect in a Topological Insulator Interfaced with a Magnetic Insulator
• Quantum anomalous Hall insulator in ionic Rashba lattice of correlated electrons
• Topological magnetic textures in magnetic topological insulators
• Scanning SQUID-on-tip microscope in a top-loading cryogen-free dilution refrigerator
• Soft-magnetic skyrmions induced by surface-state coupling in an intrinsic ferromagnetic topological insulator sandwich structure
• Mapping the phase diagram of the quantum anomalous Hall and topological Hall effects in a dual-gated magnetic topological insulator heterostructure