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

Andrew L. Yeats, Peter J. Mintun, Yu Pan, Anthony Richardella, Bob B. Buckley, Nitin Samarth, David D. Awschalom

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Abstract

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. 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.

Original languageEnglish (US)
Pages (from-to)10379-10383
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number39
DOIs
StatePublished - Sep 26 2017

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strontium titanium oxide

All Science Journal Classification (ASJC) codes

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Cite this

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abstract = "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. 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.",
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Local optical control of ferromagnetism and chemical potential in a topological insulator. / Yeats, Andrew L.; Mintun, Peter J.; Pan, Yu; Richardella, Anthony; Buckley, Bob B.; Samarth, Nitin; Awschalom, David D.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 114, No. 39, 26.09.2017, p. 10379-10383.

Research output: Contribution to journalArticle

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