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Persistent optically-induced magnetism in SrTiO3-d

In collaboration with the group of Scott Crooker at Los Alamos National Lab and Greg Haugstad of the CSE Characterization Facility, graduate student Palak Ambwani and faculty member Chris Leighton have recently reported a remarkable finding in the area of complex oxides. The team discovered that illuminating the archetypal oxide semiconductor SrTiO3 with circularly polarized light can induce and control magnetism in this nominally non-magnetic material. Most surprisingly, at cryogenic temperatures the induced magnetism persists for hours after ceasing the illumination, creating the ability to optically write, store, and read information (see image). The effect occurs only in samples deliberately prepared to have significant densities of oxygen vacancies, and the detailed results in fact implicate a localized defect complex as the fundamental origin of the effect. Work is underway to understand the nature of this defect, which could potentially hold the key to room temperature operation. The work (“Persistent optically induced magnetism in oxygen-deficient strontium titanate”) was recently published in Nature Materials. This work received partial support from a MSREC Seed award.