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Title: Local optical control of ferromagnetism and chemical potential in a topological insulator

Many proposed experiments involving topological insulators (TIs) require spatial control over time-reversal symmetry and chemical potential. We demonstrate reconfigurable micron-scale optical control of both magnetization (which breaks time-reversal symmetry) and chemical potential in ferromagnetic thin films of Cr-(Bi,Sb) 2Te 3 grown on SrTiO 3. By optically modulating the coercivity of the films, we write and erase arbitrary patterns in their remanent magnetization, which we then image with Kerr microscopy. Additionally, by optically manipulating a space charge layer in the underlying SrTiO 3 substrates, we control the local chemical potential of the films. This optical gating effect allows us to write and erase p-n junctions in the films, which we study with photocurrent microscopy. Both effects are persistent and may be patterned and imaged independently on a few-micron scale. As a result, dynamic optical control over both magnetization and chemical potential of a TI may be useful in efforts to understand and control the edge states predicted at magnetic domain walls in quantum anomalous Hall insulators.
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [2] ;  [3] ;  [1]
  1. Univ. of Chicago, Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Univ. of Chicago, Chicago, IL (United States)
  3. The Pennsylvania State Univ., University Park, PA (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 114; Journal Issue: 39; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
Air Force Research Laboratory (AFRL), Air Force Office of Scientific Research (AFOSR); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Materials Sciences and Engineering Division; US Department of the Navy, Office of Naval Research (ONR); National Science Foundation (NSF); Argonne National Laboratory, Laboratory Directed Research and Development (LDRD)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Kerr microscopy; ferromagnetism; magneto-optical recording; photocurrent microscopy; topological insulators
OSTI Identifier:
1405317

Yeats, Andrew L., Mintun, Peter J., Pan, Yu, Richardella, Anthony, Buckley, Bob B., Samarth, Nitin, and Awschalom, David D.. Local optical control of ferromagnetism and chemical potential in a topological insulator. United States: N. p., Web. doi:10.1073/pnas.1713458114.
Yeats, Andrew L., Mintun, Peter J., Pan, Yu, Richardella, Anthony, Buckley, Bob B., Samarth, Nitin, & Awschalom, David D.. Local optical control of ferromagnetism and chemical potential in a topological insulator. United States. doi:10.1073/pnas.1713458114.
Yeats, Andrew L., Mintun, Peter J., Pan, Yu, Richardella, Anthony, Buckley, Bob B., Samarth, Nitin, and Awschalom, David D.. 2017. "Local optical control of ferromagnetism and chemical potential in a topological insulator". United States. doi:10.1073/pnas.1713458114. https://www.osti.gov/servlets/purl/1405317.
@article{osti_1405317,
title = {Local optical control of ferromagnetism and chemical potential in a topological insulator},
author = {Yeats, Andrew L. and Mintun, Peter J. and Pan, Yu and Richardella, Anthony and Buckley, Bob B. and Samarth, Nitin and Awschalom, David D.},
abstractNote = {Many proposed experiments involving topological insulators (TIs) require spatial control over time-reversal symmetry and chemical potential. We demonstrate reconfigurable micron-scale optical control of both magnetization (which breaks time-reversal symmetry) and chemical potential in ferromagnetic thin films of Cr-(Bi,Sb)2Te3 grown on SrTiO3. By optically modulating the coercivity of the films, we write and erase arbitrary patterns in their remanent magnetization, which we then image with Kerr microscopy. Additionally, by optically manipulating a space charge layer in the underlying SrTiO3 substrates, we control the local chemical potential of the films. This optical gating effect allows us to write and erase p-n junctions in the films, which we study with photocurrent microscopy. Both effects are persistent and may be patterned and imaged independently on a few-micron scale. As a result, dynamic optical control over both magnetization and chemical potential of a TI may be useful in efforts to understand and control the edge states predicted at magnetic domain walls in quantum anomalous Hall insulators.},
doi = {10.1073/pnas.1713458114},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 39,
volume = 114,
place = {United States},
year = {2017},
month = {9}
}