Effect of strain on the stability and electronic properties of ferrimagnetic Fe$_{2-x}$Ti$_x$O$_3$ heterostructures from correlated band theory

Abstract

Based on density functional theory (DFT) calculations including an on-site Hubbard $U$ term we investigate the effect of substrate-induced strain on the properties of ferrimagnetic Fe$_2$O$_3$-FeTiO$_3$ solid solutions and heterostructures. While the charge compensation mechanism through formation of a mixed \fetw, \feth-contact layer is unaffected, strain can be used to tune the electronic properties of the system, e.g. by changing the position of impurity levels in the band gap. Straining hematite/ilmenite films at the lateral parameters of Al$_{2}$O$_{3}$(0001), commonly used as a substrate, is found to be energetically unfavorable as compared to films on Fe$_{2}$O$_{3}$(0001) or FeTiO$_{3}$(0001)-substrates.