Strain induced metal-insulator transition in ultrathin films of SrRuO$_3$

TL;DR

This paper investigates how strain influences the electronic and magnetic phases of ultrathin SrRuO$_3$ films, revealing a transition from insulating to metallic states that could enable novel device functionalities.

Contribution

It demonstrates that modest strain can induce a metal-insulator transition in ultrathin SrRuO$_3$ films, highlighting strain as a control parameter for electronic phases.

Findings

Ultrathin SrRuO$_3$ becomes insulating and antiferromagnetic at three monolayers.

A 1% compressive strain induces a transition to a metallic, spin-polarized state.

Strain-driven transition has potential for two-state device applications.

Abstract

The ultrathin film limit has been shown to be a rich playground for unusual low dimensional physics. Taking the example of SrRuO$_3$ 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 SrTiO$_3$. The origin of the insulating state is traced to strongly orbital dependent exchange splittings. A modest compressive strain of 1% of the SrTiO$_3$ 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.