Revealing optically induced magnetization in SrTiO3 using optically coupled SQUID magnetometry and magnetic circular dichroism

In this work, the authors study the time-and temperature-dependence of optically induced magnetization in bulk crystals of slightly oxygen-deficient SrTiO3-delta using an optically coupled superconducting quantum interference device magnetometer. Circularly-polarized sub-bandgap light is found to induce a weak (similar to 5 x 10(-7) emu) but extremely long-lived (hours) magnetic moment in SrTiO3-delta at zero magnetic field. The authors utilize this effect to demonstrate that SrTiO3-delta crystals can be used as an optically addressable magnetic memory by writing and subsequently reading magnetic patterns with light. The induced magnetization is consistent with that of a polarized ensemble of independent oxygen-vacancy-related complexes, rather than from collective or long-range magnetic order. (c) 2014 American Vacuum Society.