Electrically tuned magnetic order and magnetoresistance in a topological insulator

Abstract

The Dirac-like surface states of the topological insulators (TIs) are protected by time reversal symmetry (TRS) and exhibit a host of novel properties. Introducing magnetism into TI, which breaks the TRS, is expected to create exotic topological magnetoelectric effects. A particularly intriguing phenomenon in this case is the magnetic field dependence of electrical resistance, or magnetoresistance (MR). The intricate interplay between topological protection and broken-TRS may lead to highly unconventional MR behaviour that can find unique applications in magnetic sensing and data storage. However, so far the MR of TI with spontaneously broken TRS is still poorly understood, mainly due to the lack of well-controlled experiments. In this work, we investigate the magneto transport properties of a ferromagnetic TI thin film fabricated into a field effect transistor device. We observe an unusually complex evolution of MR when the Fermi level (EF) is tuned across the Dirac point (DP) by gate voltage. In particular, MR tends to be positive when EF lies close to the DP but becomes negative at higher energies. This trend is opposite to that expected from the Berry phase picture for localization, but is intimately correlated with the gate-tuned magnetic order. We show that the underlying physics is the competition between the topology-induced weak antilocalization and magnetism-induced negative MR. The simultaneous electrical control of magnetic order and magneto transport facilitates future TI-based spintronic devices.

4 figures, supplementary information included

References in corpus (5)

• Topological Field Theory of Time-Reversal Invariant Insulators
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Gate-Voltage Control of Chemical Potential and Weak Anti-localization in Bismuth Selenide
• Impurity effect on weak anti-localization in the topological insulator Bi2Te3
• Surface quantized anomalous Hall current and magneto-electric effect in magnetically disordered topological insulators

Cited by in corpus (11)

• Dimensional Crossover Induced Topological Hall Effect in a Magnetic Topological Insulator
• Electrically Tunable Magnetism in Magnetic Topological Insulators
• Characterizing the Structure of Topological Insulator Thin Films
• Weak Localization and Antilocalization in Topological Materials with Impurity Spin-Orbit Interactions
• Magnetic quantum phase transition in Cr-doped Bi2(SexTe1-x)3 driven by the Stark effect
• Quantum Transport in Weyl Semimetal Thin Films in the Presence of Spin-Orbit Coupled Impurities
• Evolution of Dopant-Concentration-Induced Magnetic Exchange Interaction in Topological Insulator Thin Films
• Ambi-chiral anomalous Hall effect in magnetically doped topological insulators
• Vector Chirality $\kappa$ Driven Topological Phase Transition and the Associated Anomalous Hall Conductivity Tuning in a Non-Collinear Antiferromagnet
• Environmental Doping-Induced Degradation of the Quantum Anomalous Hall Insulators
• Revisiting magnetic exchange interactions in transition metal doped Bi${}_2$Se${}_3$ using DFT+MFT