Pressure-induced electronic mixing and enhancement of ferromagnetic ordering in EuX (X=Te, Se, S, O) magnetic semiconductors

TL;DR

This study investigates how pressure and chemical substitution influence the electronic structure and ferromagnetic ordering in EuX magnetic semiconductors, revealing orbital mixing and competing exchange interactions.

Contribution

It demonstrates that pressure-induced lattice contraction enhances ferromagnetism via Eu 4f-5d orbital mixing, while anion substitution introduces competing exchange pathways, providing insights for magnetic property tuning.

Findings

Lattice contraction under pressure enhances ferromagnetic ordering.

Anion substitution affects exchange interactions through spin-polarized p states.

Orbital mixing correlates with increased ferromagnetic transition temperatures.

Abstract

The pressure- and anion-dependent electronic structure of EuX (X=Te, Se, S, O) monochalcogenides is probed with element- and orbital-specific X-ray absorption spectroscopy in a diamond anvil cell. An isotropic lattice contraction enhances the ferromagnetic ordering temperature by inducing mixing of Eu 4{\it f} and 5{\it d} electronic orbitals. Anion substitution (Te $\to$ O) enhances competing exchange pathways through spin-polarized anion {\it p} states, counteracting the effect of the concomitant lattice contraction. The results have strong implications for efforts aimed at enhancing FM exchange interactions in thin films through interfacial strain or chemical substitutions.