Optically manipulating ferromagnetism in Cr-doped topological insulators (TIs)

ORAL

Abstract

Optically manipulating ferromagnetic materials has been shown to be a promising route to opto-spintronic applications. Using a combination of optically-enabled transport measurements and scanning tunneling spectroscopic (STS) measurements in the presence of circularly polarized (CP) light, we found an enhancement of magnetization in 10% Cr-doped (BixSb1-x)2Te3 bilayer heterostructures which consisted of a pure layer (BixSb1-x)2Te3 on top of a 10% Cr-doped (BixSb1-x)2Te3 layer. Measurements of the anomalous Hall resistance revealed an increase in Rxy and a decrease in longitudinal resistance Rxx in the bilayer magnetic TI system under CP light (wavelengths λ = 1600 ~ 1700 nm). In contrast, both Rxx and Rxy were suppressed under CP light for uniformly Cr-doped (BixSb1-x)2Te3. To understand the microscopic origin of these results, we performed spatially resolved STS studies on the surface state of magnetic TIs as a function of temperature and magnetic field. We further conducted optically-assisted STS studies to spatially map out the CP light-induced spectral changes to the surface state. The physical implications from correlating the spatially resolved STS under CP light with findings from macroscopic Rxx and Rxy will be discussed.

*This work is jointly supported by ARO and NSF.

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Presenters

  • Adrian Llanos

    • Department of Applied Physics, Caltech

Authors

  • Adrian Llanos

    • Department of Applied Physics, Caltech

  • Chien-Chang Chen

    • Department of Physics, Caltech

  • Marcus L Teague

    • Caltech
    • Department of Physics, Caltech

  • Xiaoyu Che

    • Electrical and Computer Engineering, University of California, Los Angeles
    • Department of Electrical Engineering, University of California Los Angeles

  • Peng Zhang

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

  • Lei Pan

    • Department of Electrical Engineering, University of California Los Angeles

  • Kang L. Wang

    • Department of Electrical and Computer Engineering, University of California, Los Angeles
    • UCLA
    • Department of Electrical Engineering, University of California Los Angeles
    • University of California at Los Angeles

  • Nai-Chang Yeh

    • Caltech
    • Department of Physics, Caltech