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arXiv · 1503.01523

Persistent Optical Gating of a Topological Insulator

Andrew L. Yeats·Yu Pan·Anthony Richardella·Peter J. Mintun·Nitin Samarth·David D. Awschalom
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Abstract

Topological insulators (TIs) have attracted much attention due to their spin-polarized surface and edge states, whose origin in symmetry gives them intriguing quantum-mechanical properties. Robust control over the chemical potential of TI materials is important if these states are to become useful in new technologies, or as a venue for exotic physics. Unfortunately, chemical potential tuning is challenging in TIs in part because the fabrication of electrostatic top-gates tends to degrade material properties and the addition of chemical dopants or adsorbates can cause unwanted disorder. Here, we present an all-optical technique which allows persistent, bidirectional gating of a (Bi,Sb)2Te3 channel by optically manipulating the distribution of electric charge below its interface with an insulating SrTiO3 substrate. In this fashion we optically pattern p-n junctions in a TI material, which we subsequently image using scanning photocurrent microscopy. The ability to dynamically write and re-write mesoscopic electronic structures in a TI may aid in the investigation of the unique properties of the topological insulating phase. The optical gating effect may be adaptable to other material systems, providing a more general mechanism for reconfigurable electronics.

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Andrew L. Yeats, Yu Pan, Anthony Richardella, Peter J. Mintun, Nitin Samarth, David D. Awschalom. 2015-03-05. Persistent Optical Gating of a Topological Insulator. https://doi.org/10.1126/sciadv.1500640

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