Unexpected Effectiveness of Berezinskii-Kosterlitz-Thouless Description of Electron Paramagnetic Resonance Linewidth Behaviour in the 3-Dimensional Manganite Bi$_{0.5}$Sr$_{0.5}$Mn$_{0.9}$Cr$_{0.1}$O$_3$

TL;DR

This study demonstrates that the BKT model effectively describes the EPR linewidth behavior in certain 3D manganites, revealing an unexpected 2D-like magnetic anisotropy induced by the applied magnetic field.

Contribution

It shows that the BKT model can describe EPR linewidths in 3D manganites, highlighting an induced 2D anisotropy not previously recognized.

Findings

BKT model fits EPR linewidth data in 3D manganites

Effective 2D XY anisotropy induced by magnetic field

Field dependence of BKT correlations observed in related compounds

Abstract

We find that the temperature dependence of the Electron Paramagnetic Resonance (EPR) linewidth observed in Bi$_{0.5}$Sr$_{0.5}$Mn$_{0.9}$Cr$_{0.1}$O$_3$ (BSMCO), as well as in certain other 3-dimensional manganites undergoing antiferromagnetic transitions is satisfactorily described by the Berezinskii-Kosterlitz-Thouless (BKT) model. We understand this unexpected result in terms of an effective 2-dimensional XY easy plane anisotropy induced by the magnetic field applied in the EPR experiment. This conclusion is supported by the field dependence of the BKT correlations observed in the quasi two-dimensional antiferromagnetic compound BaNi$_{2}$V$_{2}$O$_{8}$.