Rewritable Optical Memory Based on Sign Switching of Magnetoresistance

Abstract Discovering ways to control magnetic states by light is very attractive for prospective applications of optical–magnetic sensing and recording. Although several studies have demonstrated the light‐induced switching of magnetization, the magnetoresistance effect was seldom thought to depend on light illumination. A light‐induced magnetoresistance sign switching the resulting writable optical memory are described. A practical method is developed to form a p‐n junction at the interface of a p‐type amorphous carbon film and a quasi‐2D electron gas on an SrTiO 3 surface. When illuminated, the as‐formed junction exhibits a clear transition from positive to negative magnetoresistance. A change of optical intensity influences the response time, but not the final value of the negative magnetoresistance. It is also found that, after a light pulse, the negative magnetoresistance state tends to persist, indicating a longstanding memory for an optical signal. This points to a new direction for studying light‐induced magnetoresistance switching, which could lead to the development of new memory devices.