Magnetoelastic coupling descriptor for high-throughput ab initio search of magnetocaloric materials

Abstract

We use Landau theory of phase transitions to design a magnetoelastic coupling descriptor that can identify magnetic materials on the brink of a first-order transition, where a strong magnetocaloric effect (MCE) can arise. The descriptor can be computed from electronic structure calculations and requires structural optimization in the paramagnetic state, which we model using special quasi-random collinear spin configurations. We first evaluate the descriptor for a set of known magnetocaloric materials and identify compounds in which the MCE is driven by magnetoelastic coupling. We then apply the descriptor in a high-throughput \emph{ab initio} screening of magnetic L1${}_2$ compounds. This search identifies the L1${}_2$ cubic phases of Mn${}_3$Ge and Mn${}_3$Sb as materials with strong magnetoelastic coupling and potential for a large magnetocaloric response.

9 pages, 3 figures