Controlling the magnetism of the Mott insulator LaTiO₃ by interface engineering

We present an investigation of the magnetic, electronic and structural properties of thin films of the Mott insulator LaTiO₃ (LTO) grown on insulating SrTiO₃ (STO) and LaAlO₃ (LAO) substrates. As in the case of LAO/STO interface, high mobility 2DEG and superconductivity have been reported at LTO/STO interfaces, while the LTO/LAO interfaces remain insulating. Using depth resolved low energy muon spin relaxation (LE-μSR) and β-detected NMR (β-NMR) we find that while LTO undergoes antiferromagnetic ordering on LAO it becomes non-magnetic when grown on STO. The observed magnetic transition temperature in the film, ~75 K, is significantly suppressed compared to bulk LTO (~140 K). Surprisingly, we detect a clear interface proximity effect to the LTO/STO interface, where the magnetism becomes gradually stronger as we probe further away from the interface. The effect is attributed to charge transfer effects at the LTO/STO interface. The results demonstrate the potential of tunability of the magnetic and electronic properties of a Mott insulator by interface engineering.