Strain-Driven Orbital and Magnetic Orders and Phase Separation in Epitaxial Half-Doped Manganite Films for Tunneling Devices

Abstract

A strong theme in applied physics research is the control of magnetism with electric (rather than magnetic) fields. Giant electroresistance can be used to this end in a ferroelectric tunnel junction (FTJ) by adding a material in which a metal-insulator transition is triggered by polarization switching in the ferroelectric. Half-doped manganites like La${}_{0.5}$(Sr,Ca)${}_{0.5}$MnO${}_{3}$ seem ideal for this, but epitaxial strain can profoundly modify their ground state. The authors use ${}^{55}$Mn NMR to study orbital and magnetic orderings in such epitaxial films, and they evaluate how the films evolve with strain and electronic bandwidth. Their results are key to engineering large tunneling electroresistance in FTJs.