Revisiting the high-field phase diagram of the topological cubic helimagnet SrFeO$_{3}$

TL;DR

This study investigates the complex magnetic phases of SrFeO₃, revealing the role of electronic itinerancy and anisotropy in stabilizing multiple-Q magnetic structures through experimental and theoretical analysis.

Contribution

It introduces an effective spin Hamiltonian including anisotropy and interactions, explaining the emergence of multiple-Q phases in SrFeO₃.

Findings

Identified the field-orientation dependence of the magnetic phase diagram.

Established an effective spin Hamiltonian with anisotropy and interactions.

Detected magnetoelastic signatures of a valence transition at high fields.

Abstract

The cubic perovskite SrFeO$_{3}$ is a prototypical centrosymmetric itinerant magnet that hosts a quadruple-${\mathbf Q}$ hedgehog-antihedgehog lattice and exhibits a complex magnetic-field-temperature phase diagram. Yet, the microscopic mechanism underlying the emergence of its versatile multiple-${\mathbf Q}$ phases remains unresolved. Here, we elucidate the field-orientation dependence of the magnetic phase diagram and establish an effective spin Hamiltonian for SrFeO$_{3}$ that incorporates a cubic single-ion anisotropy together with bilinear and biquadratic interactions in momentum space. In addition, we observe magnetoelastic signatures of a first-order valence transition upon entering the forced FM phase at 40 T, which would be attributed to the suppression of negative charge transfer. These findings emphasize the pivotal importance of electronic itinerancy arising from the formation of a ligand-hole band in stabilizing multiple-${\mathbf Q}$ phases.