Resonant magneto-optic Kerr effect in the magnetic topological insulator Cr:(Sb${}_x$,Bi${}_{1-x}$)${}_2$Te${}_3$

Abstract

We report measurements of the polar Kerr effect, proportional to the out-of-plane component of the magnetization, in thin films of the magnetically doped topological insulator $({\text{Cr}}_{0.12}{\text{Bi}}_{0.26}{\text{Sb}}_{0.62}{)}_2{\text{Te}}_3$. Measurements of the complex Kerr angle, ${\Theta }_K$, were performed as a function of photon energy in the range $0.8\text{ eV}<\hslash \omega <3.0\text{ eV}$. We observed a peak in the real part of ${\Theta }_K(\omega )$ and zero crossing in the imaginary part that we attribute to resonant interaction with a spin-orbit avoided crossing located $\approx$ 1.6 eV above the Fermi energy. The resonant enhancement allows measurement of the temperature and magnetic field dependence of ${\Theta }_K$ in the ultrathin film limit, $d\ge 2$ quintuple layers. We find a sharp transition to zero remanent magnetization at 6 K for $d<8$~QL, consistent with theories of the dependence of impurity spin interactions on film thickness and their location relative to topological insulator surfaces.

6 pages, 5 figures

References in corpus (11)

• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Topological Field Theory of Time-Reversal Invariant Insulators
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Scale-Invariant Dissipationless Chiral Transport in Magnetic Topological Insulators beyond the Two-Dimensional Limit
• Precise quantization of anomalous Hall effect near zero magnetic field
• Imaging Dirac-Mass Disorder from Magnetic Dopant-Atoms in the Ferromagnetic Topological Insulator Cr${}_x$(Bi${}_{0.1}$Sb${}_{0.9}$)${}_{2-x}$Te${}_3$
• Ordering of magnetic impurities and tunable electronic properties of topological insulators
• Metal-to-Insulator Switching in Quantum Anomalous Hall States
• Electrically Tunable Magnetism in Magnetic Topological Insulators
• Unoccupied Topological States on Bismuth Chalcogenides
• Optical properties of magnetically doped ultra-thin topological insulator slabs

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• Observation of topological Faraday and Kerr rotations in quantum anomalous Hall state by terahertz magneto-optics
• Unoccupied Topological Surface State in MnBi${}_2$Te${}_4$