A first principles study of magnetism in Pd$_{3}$Fe under pressure

TL;DR

This study uses first-principles calculations to investigate how pressure affects magnetism in Pd3Fe, challenging previous ideas and suggesting a transition to non-collinear magnetic states as the cause of observed anomalies.

Contribution

It provides a detailed theoretical analysis of magnetic phase transitions in Pd3Fe under pressure, proposing a new explanation for invar behavior.

Findings

No ferromagnetic to spin-disordered transition occurs under pressure.

Anomalies may be due to transition from collinear to non-collinear magnetic states.

First-principles calculations support the non-collinear transition hypothesis.

Abstract

Recent experiments on Pd$_{3}$Fe intermetallics [Phys. Rev. Lett. 102, 237202 (2009)] have revealed that the system behaves like a classical invar alloy under high pressure. The experimental pressure-volume relation suggests an anomalous volume collapse and a substantial increase in bulk modulus around the pressure where invar behavior is observed. With the help of first-principles density functional theory based calculations, we have explored various magnetic phases (ferromagnetic, fully and partially disordered local moment, spin spiral) in order to understand the effect of pressure on magnetism. Our calculations reveal that the system does not undergo a transition from a ferromagnetic to a spin-disordered state as was thought to be the possible mechanism to explain the invar behavior of this system. We rather suggest that the anomaly in the system could possibly be due to the transition from a collinear state to non-collinear magnetic states upon the application of pressure.