Interface-induced magnetism in perovskite quantum wells

Abstract

We investigate the angular dependence of the magnetoresistance of thin (1 nm), metallic SrTiO${}_{3}$ quantum wells epitaxially embedded in insulating, ferrimagnetic GdTiO${}_{3}$ and insulating, antiferromagnetic SmTiO${}_{3}$, respectively. The SrTiO${}_{3}$ quantum wells contain a high density of mobile electrons (\ensuremath{\sim}$7\ifmmode\times\else\texttimes\fi{}{10}^{14}\phantom{\rule{0.28em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}2}$). We show that the longitudinal and transverse magnetoresistance in the structures with GdTiO${}_{3}$ are consistent with anisotropic magnetoresistance, and thus indicative of induced ferromagnetism in the SrTiO${}_{3}$, rather than a nonequilibrium proximity effect. Comparison with the structures with antiferromagnetic SmTiO${}_{3}$ shows that the properties of thin SrTiO${}_{3}$ quantum wells can be tuned to obtain magnetic states that do not exist in the bulk material.