Magnetism and electronic order in SmTiO$_{\mathrm{3}}$ quantum well heterostructures

Complex oxide heterostructures that possess high density interfacial electron gases due to charge discontinuities between neighboring layers provide a unique platform with which to study correlated electron physics. In heterostructures containing band insulator SrTiO$_{\mathrm{3}}$ and Mott insulating rare earth titanate layers, it has been shown that tuning relative layer thicknesses can in turn tune both the electronic and magnetic properties found in each layer type, leading to exotic metal-insulator transitions and electronic symmetry breaking in the interleaving quantum wells. Here we use a combination of resonant x-ray reflectometry (RXR), polarized neutron reflectometry (PNR), and muon spin rotation (muSR) to probe the electronic and magnetic properties of SmTiO$_{\mathrm{3}}$ thin films and SrTiO$_{\mathrm{3}}$-SmTiO$_{\mathrm{3}}$ heterostructures. RXR measurements demonstrate the effect of tuning both SrTiO$_{\mathrm{3}}$ and SmTiO$_{\mathrm{3}}$ layer thicknesses on the electronic structure, and our combined PNR and muSR results resolve the freezing of interface-induced free electrons within the SrTiO$_{\mathrm{3}}$ quantum wells below a critical temperature. The correlations between our scattering results and previously reported anomalous transport in SrTiO$_{\mathrm{3}}$-SmTiO$_{\mathrm{3}}$ heterostructures will be discussed.