Writing topological devices with light

A collaboration with the Awschalom group (Chicago) produced a surprising discovery: illumination of topological insulator films on strontium titanate substrates provides a way to optically pattern persistently doped regions of the film. This provides a potentially powerful scheme for writing and erasing circuits that contain topological insulator devices [Yeats et al., Science Advances, 2015] . See also these press releases from Chicago and Penn State.

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Tunneling out of a false vacuum

A collaborative experiment with the Ong group (Princeton) shows that at low temperature (T < 150 mK), the transition between Chern states in a quantum anomalous Hall insulator occurs via sudden macroscopic magnetization reversal events. These events are detected as sudden discrete jumps in the anomalous Hall resistance and their variation with temperature and chemical potential suggest a quantum tunneling out of a false vacuum [Liu et al., Science Advances, 2016].

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