Exchange bias and its phase reversal in the zero magnetization admixed rare earth intermetallics

TL;DR

This paper investigates exchange bias and its phase reversal in admixed rare earth intermetallics, revealing temperature-dependent magnetic compensation and conduction electron polarization reversal linked to phase changes in the exchange bias.

Contribution

It introduces a new class of admixed rare earth intermetallics exhibiting temperature-driven phase reversal of exchange bias and conduction electron polarization.

Findings

Exchange bias reverses sign across a characteristic temperature.

Magnetic moments of dissimilar RE ions get antiferromagnetically coupled.

Conduction electron polarization also reverses sign across the compensation temperature.

Abstract

Exchange bias effect is an important attribute in several device applications. Traditionally, it is discussed as a form of exchange anisotropy at the interface between the ferromagnetic/antiferromagnetic layers of two distinct systems. We report here on the magnetically ordered alloys possessing the feature of unidirectional anisotropy, which reverses its sign across a characteristic temperature. These are admixed rare earth intermetallics, comprising two dissimilar rare earth (RE) ions, belonging to the two different halves of the 4f-series and imbibing the notion of ferromagnetic coupling between the spins of all 4f-rare earth ions and that of the conduction electrons. Magnetic moments of dissimilar RE ions in such admixed alloys, however, get antiferromagnetically coupled and they display magnetic compensation feature such that the field induced reversal in the orientation of the magnetic moments of dissimilar rare earth ions happens across the compensation temperature (Tcomp). Above a threshold field, the conduction electron polarization also reverses its sign across Tcomp, this is argued to correlate with the observed phase reversal in the exchange bias field.