title: Persistent optically induced magnetism in oxygen-deficient strontium titanate.
abstract: Strontium titanate (SrTiO3) is a foundational material in the emerging field of complex oxide electronics. Although its bulk electronic and optical properties are rich and have been studied for decades, SrTiO3 has recently become a renewed focus of materials research catalysed in part by the discovery of superconductivity and magnetism at interfaces between SrTiO3 and other non-magnetic oxides. Here we illustrate a new aspect to the phenomenology of magnetism in SrTiO3 by reporting the observation of an optically induced and persistent magnetization in slightly oxygen-deficient bulk SrTiO3-δ crystals using magnetic circular dichroism (MCD) spectroscopy and SQUID magnetometry. This zero-field magnetization appears below ~18 K, persists for hours below 10 K, and is tunable by means of the polarization and wavelength of sub-bandgap (400-500 nm) light. These effects occur only in crystals containing oxygen vacancies, revealing a detailed interplay between magnetism, lattice defects, and light in an archetypal complex oxide material.
authors.affiliation: National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: W D
authors.initials: WD
authors.lastname: Rice
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: P
authors.initials: P
authors.lastname: Ambwani
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund, D-44227 Dortmund, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Bombeck
authors.affiliation: Materials Physics and Applications, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Thompson
authors.affiliation: Characterization Facility, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: G
authors.initials: G
authors.lastname: Haugstad
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: C
authors.initials: C
authors.lastname: Leighton
authors.affiliation: National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Crooker