Strain-engineered magnetic order in (LaMnO${}_3$)${}_n$/(SrMnO${}_3$)${}_{2n}$ superlattices

Abstract

Using first-principles calculations based on the density functional theory, we show a strong strain dependence of magnetic order in (LaMnO${}_3$)${}_n$/(SrMnO${}_3$)${}_{2n}$ (001) superlattices with $n=1,2$. The epitaxial strain lifts the degeneracy of Mn $e_g$ orbitals, thus inducing an inherent orbital order, which in turn strongly affects the ferromagnetic double exchange of itinerant $e_g$ electrons, competing with the antiferromagnetic superexchange of localized $t_{2g}$ electrons. For the case of tensile strain induced by SrTiO${}_3$ (001) substrate, we find that the ground state is A-type antiferromagnetic and $d_{x^2-y^2}$ orbital ordered, which is in excellent agreement with recent experiments [S. J. May {\it et al.}, Nature Materials {\bf 8}, 892 (2009)]. Instead, for the case of compressive strain induced by LaAlO${}_3$ (001) substrate, we predict that the ground state is C-type antiferromagnetic and $d_{3z^2-r^2}$ orbital ordered.

The paper is accepted for publication in Phys. Rev. B

References in corpus (2)

• Metal-insulator transition in $(LaMn{O}_3{)}_{2n}/(SrMn{O}_3{)}_n$ superlattices
• Optical Properties of (SrMnO3)n/(LaMnO3)2n superlattices: an insulator-to-metal transition observed in the absence of disorder

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• Magnetic and Orbital Order in ($R$MnO${}_3$)${}_n$/($A$MnO${}_3$)${}_{2n}$ Superlattices Studied via a Double-Exchange Model with Strain
• (LaTiO${}_3$)${}_n$/(LaVO${}_3$)${}_n$ as a model system for unconventional charge transfer and polar metallicity
• Magnetism and electronic structure of ($001$)- and ($111$)-oriented LaTiO${}_3$ bilayers sandwiched in LaScO${}_3$ barriers
• Orientation-dependent magnetism and orbital structure of strained YTiO${}_3$ films on LaAlO${}_3$ substrates