Magnetic properties of bilayer Sr${}_3$Ir${}_2$O${}_7$: role of epitaxial strain and oxygen vacancies

Abstract

Using {\it ab initio} methods, we investigate the modification of the magnetic properties of the $m=2$ member of the strontium iridates Ruddlesden-Popper series Sr${}_{m+1}$Ir${}_m$O${}_{3m+1}$, bilayer Sr${}_3$Ir${}_2$O${}_7$, induced by epitaxial strain and oxygen vacancies. Unlike the single layer compound Sr${}_2$IrO${}_4$, which exhibits a robust in-plane magnetic order, the energy difference between in-plane and out-of-plane magnetic orderings in Sr${}_3$Ir${}_2$O${}_7$ is much smaller and it is expected that small external perturbations could induce magnetic transitions. Our results indicate that epitaxial strain yields a spin-flop transition, that is driven by the crossover between the intralayer $J_1$ and interlayer $J_2$ magnetic exchange interactions upon compressive strain. While $J_1$ is essentially insensitive to strain effects, the strength of $J_2$ changes by one order of magnitude for tensile strains $\ge$ 3~\%. In addition, our study clarifies that the unusual in-plane magnetic response observed in Sr${}_3$Ir${}_2$O${}_7$ upon the application of an external magnetic field originates from the canting of the local magnetic moments due to oxygen vacancies, which tilt the octahedral networks - thereby allowing for noncollinear spin configurations.

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Cited by in corpus (4)

• Dimensionality-strain phase diagram of strontium iridates
• The role of defects in the metal-insulator transition in VO${}_2$ and V${}_2$O${}_3$
• First-Principles Calculation of Spin and Orbital Contributions to Magnetically Ordered Moments in Sr${}_2$IrO${}_4$
• Epitaxial stabilization of Sr3Ir2O7 thin films