Non-collinear magnetic ordering in compressed FePd$_3$ ordered alloy: a first principles study

TL;DR

This study uses first-principles calculations to explore how pressure induces non-collinear magnetic ordering in FePd$_3$, revealing complex magnetic phases influenced by Pd polarization and higher-order interactions.

Contribution

It introduces an extended Heisenberg model including biquadratic terms to accurately describe pressure-induced non-collinear magnetism in FePd$_3$.

Findings

Pressure favors non-collinear spin arrangements.

Strong dependence of Fe-Fe exchange on Pd polarization.

Identification of a complex 'triple-Q' magnetic ground state.

Abstract

By means of ab initio calculations based on the density functional theory we investigated magnetic phase diagram of ordered FePd$_3$ alloy as a function of external pressure. Considering several magnetic configurations we concluded that the system under pressure has a tendency to non-collinear spin alignment. Analysis of the Heisenberg exchange parameters $J_{ij}$ revealed strong dependence of iron-iron magnetic couplings on polarization of Pd atoms. To take into account the latter effect we built an extended Heisenberg model with higher order (biquadratic) terms. Minimizing the energy of this Hamiltonian, fully parameterized using the results of ab initio calculations, we found a candidate for a ground state of compressed FePd$_3$, which can be seen as two interpenetrating "triple-Q" phases.