Weak ferromagnetism linked to the high-temperature spiral phase of YBaCuFeO5

TL;DR

This study investigates the magnetic properties of YBaCuFeO5, revealing weak ferromagnetism linked to its high-temperature spiral phase, which could enable magnetic control of its multiferroic properties for technological applications.

Contribution

First detailed phase diagram of YBaCuFeO5 under magnetic fields, showing coexistence of spiral order and weak ferromagnetism, advancing understanding of its magnetoelectric potential.

Findings

Spiral order remains stable under magnetic fields up to 9 T.

Weak ferromagnetism coexists with the spiral phase.

Magnetic fields can potentially control spiral orientation.

Abstract

The layered perovskite YBaCuFeO5 is a rare example of cycloidal spiral magnet whose ordering temperature Tspiral can be tuned far beyond room temperature by adjusting the degree of Cu2+/Fe3+ chemical disorder in the structure. This unusual property qualifies this material as one of the most promising spin-driven multiferroic candidates. However, very little is known about the response of the spiral to magnetic fields, crucial for magnetoelectric cross-control applications. Using bulk magnetization and neutron powder diffraction measurements under magnetic fields up to 9 T we report here the first temperature-magnetic field phase diagram of this material. Besides revealing a strong stability of the spiral state, our data uncover the presence of weak ferromagnetism coexisting with the spiral modulation. Since ferromagnets can be easily manipulated with magnetic fields, this observation opens new perspectives for the control of the spiral orientation, directly linked to the polarization direction, as well as for a possible future use of this material in technological applications.