Strain-induced metal-insulator transition in ultrathin films of SrRuO₃

Abstract

The ultrathin film limit has been shown to be a rich playground for unusual low-dimensional physics. Taking the example of SrRuO₃, which is ferromagnetic and metallic at the bulk limit, one finds that it becomes antiferromagnetic and insulating at the three-monolayers limit when grown on SrTiO3. The origin of the insulating state is traced to strongly orbital-dependent exchange splittings. A modest compressive strain of 1% of the SrTiO₃ substrate is then found to drive the system into a highly confined two-dimensional 100% spin polarized metallic state. This metal-insulator transition driven by a modest strain could be useful in two-state device applications.