Revealing Optically Induced Magnetization in SrTiO$_3$ using Optically   Coupled SQUID Magnetometry and Magnetic Circular Dichroism
  In this work, we study the time- and temperature-dependence of optically induced magnetization in bulk crystals of slightly oxygen-deficient SrTiO$_{3-\delta}$ using an optically coupled SQUID magnetometer. We find that a weak ($\sim$5$\times$10$^{-7}$~emu) but extremely long-lived (hours) magnetic moment can be induced in SrTiO$_{3-\delta}$ at zero magnetic field by circular-polarized sub-bandgap light. We utilize this effect to demonstrate that SrTiO$_{3-\delta}$ 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. 
W. D. Rice, P. Ambwani, J. D. Thompson, C. Leighton, S. A. Crooker
cond-mat.mtrl-sci cond-mat.mes-hall