Ferromagnetism in SrTiO$_{3}$ Single Crystals Induced by Laser irradiation

SrTiO$_{3}$ (STO) is diamagnetic in pristine state, important in emerging field of complex oxide electronics. No attention has been paid to explore the magnetic properties of STO crystal upon laser irradiation/annealing. In this presentation, we demonstrate [1-2] that STO single crystals show ferromagnetic order up to 400 K upon KrF (248 nm) laser irradiation. The high resolution x-ray photo emission spectroscopy (XPS) measurements reveal a strong shift of Sr-, Ti- and O-related peaks. X-ray diffraction (XRD) of laser annealed STO does not reveal a signature of either secondary magnetic or amorphous phases. 300 K X-band ($\sim$ 9.543 GHz) angle-dependent electron paramagnetic resonance (EPR) measurements showed no evidence of additional magnetic peaks up on laser irradiation. XPS and EPR data did not provide a strong evidence of Ti$^{3+}$ formation upon laser annealing. No differences in the visible 300 K Raman spectra of pristine and laser annealed STO are noticed. Interestingly, the magnetic moment is decreased by almost 10-fold upon oxygen annealing of laser annealed STO, inferring that oxygen vacancies play an important role in establishing the observed ferromagnetism.\\[4pt] [1] S.S. Rao et al Appl. Phys. Lett. \textbf{105}, 042403 (2014); J. Appl. Phys., \textbf{116}, 094103 (2014).