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Title: Resonant magneto-optic Kerr effect in the magnetic topological insulator Cr:(Sb x,Bi 1–x) 2Te 3

Here, 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 (Cr 0.12Bi 0.26Sb 0.62) 2Te 3. Measurements of the complex Kerr angle ΘK were performed as a function of photon energy in the range 0.8eV < ℏω < 3.0eV. We observed a peak in the real part of Θ K(ω) and zero crossing in the imaginary part that we attribute to a resonant interaction with a spin-orbit avoided crossing located ≈ 1.6 eV above the Fermi energy. The resonant enhancement allows measurement of the temperature and magnetic field dependence of Θ K in the ultrathin film limit, d ≥ 2 quintuple layers (QL). 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.
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4] ;  [4] ;  [4] ;  [4] ;  [4]
  1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Simon Fraser Univ., Burnaby, BC (Canada)
  3. Univ. of California, Los Angeles, CA (United States)
  4. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 1098-0121; PRBMDO
Grant/Contract Number:
AC02-76SF00515; AC02-05CH11231
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 92; Journal Issue: 21; Journal ID: ISSN 1098-0121
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1234116; OSTI ID: 1439980