Tuning the magnetism in bilayers of magnetic topological insulators (TIs) with a back gate and circularly polarized light

ORAL

Abstract

Studies of MBE-grown magnetic bilayers revealed the appearance of spatially inhomogeneous surface state (SS) gap below Tc2D (>~210 K) by scanning tunneling spectroscopy (STS) and a bulk Curie temperature below Tc3D~35 K by anonymous Hall effect (AHE) measurements. The bilayer samples consisted of 1-QL of pure TI on top of 6-QL of Cr-doped TI, where TI was either Bi2Se3 or (Bi,Sb)2Te3. Strong magnetic fields normal to the TI bilayers were found to enhance the homogeneity of the SS gap distribution. On the other hand, topological spin textures associated with isolated magnetic impurities were observed along the boundary of gapped and gapless SS in zero fields, which disappeared under high magnetic fields. To better elucidate the microscopic mechanism of proximity-induced magnetism in the bilayer TIs, we investigate the interplay of circularly polarized light and external magnetic fields on the SS gap homogeneity and the values of Tc2D and Tc3D by both STS and AHE measurements. We further evaluate the effect of circularly polarized light on the two-level spectral resonances of isolated SS magnetic impurities and examine the effect of tuning the Fermi level via a back gate on inducing correlations among magnetic impurities.

C.-C. Chen et al., New J. Phys. 17, 113042 (2015).

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Presenters

  • Chien-Chang Chen

    Physics, Caltech

Authors

  • Chien-Chang Chen

    Physics, Caltech

  • Adrian Llanos

    Applied Physics and Materials Science, Caltech

  • Ben Seddon

    Physics, University of Cambridge

  • Marcus Teague

    Physics, Caltech, Physics, Califonia Institude of Technology

  • Nai-Chang Yeh

    Physics, Caltech, Physics, Califonia Institude of Technology, Caltech

  • Lei Pan

    Univ of California - Los Angeles, Department of Electrical Engineering, University of California, Los Angeles, University of California Los Angeles, UCLA, Electrical Engineering, UCLA

  • Koichi Murata

    Univ of California - Los Angeles, Electrical Engineering, UCLA

  • Kang Wang

    University of California, Los Angeles, Univ of California - Los Angeles, Department of Electrical Engineering, University of California, Los Angeles, Department of Electrical Engineering, UCLA, University of California Los Angeles, UCLA, Department of Electrical Engineering, Univ of California - Los Angeles, Electrical and Computer Engineering, University of California, Los Angeles, Electrical Engineering, UCLA