Magneto-Transport Study of Magnetic/Nonmagnetic Topological Insulator Heterostructures
ORAL
Abstract
Breaking time-reversal symmetry in a topological insulator (TI) by a magnetic perturbation can give rise to a variety of exotic quantum phenomena such as quantum anomalous Hall effect. Since the surface states of TIs have a spin helical massless Dirac structure, undoped TI films usually show weak antilocalization (WAL) quantum corrections to diffusive transport, characterized by a positive magnetoresistance (MR). Here, we fabricate magnetically doped TI films on pristine TI films with different thicknesses to form magnetic/nonmagnetic TI heterostructures and systematically study their magneto-transport properties. When the thickness of the TI layer is ≤2QL, the MR shows a typical butterfly shape due to domain wall scattering. However, when the thickness of the TI layer is ≥ 3QL, the MR is suppressed, similar to the WAL cusp, but near the magnetization reversal regime. We speculate that this “dip” in MR near the coercive field is a result of the coexistence of the gapless surface state of the TI layer and the ferromagnetic order in the magnetic TI layer. Our study provides new insights into magneto-transport phenomena in the presence of a superposition of gapped and gapless surface states.
*This work is supported by 2DCC-MIP, DOE, ONR, and the Alfred P. Sloan Research Fellowship.
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Presenters
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Di Xiao
- Physics, Penn State University
- Physics, The Pennsylvania State University
- Department of Physics, The Pennsylvania State University
- Pennsylvania State University
- Department of Physics, Pennsylvania State University