Spin switching and unusual exchange bias in the single-crystalline GdCrO3 compensated ferrimagnet

Abstract

An unusual exchange bias (EB) effect in single-crystalline $\mathrm{GdCr}{\mathrm{O}}_{3}$ compensated ferrimagnet (fM), composed of two antiferromagnetically coupled Gd and Cr sublattices, presenting two opposite ferromagnetic (FM) moments, is reported. It is shown that the temperature- or field-induced fast reversal of the net FM moment in $\mathrm{GdCr}{\mathrm{O}}_{3}$ may be identified as a switching between two opposite spin configurations, attendant with abrupt drop in Zeeman energy $\ensuremath{\approx}{k}_{\mathrm{B}}(7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\phantom{\rule{0.16em}{0ex}}\mathrm{K})$ per formula unit. It was found that the FM moment reversal is exchange biased in the narrow temperature interval above the compensation temperature ${T}_{\mathrm{comp}}=144\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. Namely, the EB field emerges and diverges upon approaching ${T}_{\mathrm{comp}}$ at temperatures $Tg{T}_{\mathrm{comp}}$ while unexpectedly it collapses to zero below ${T}_{\mathrm{comp}}$. This is in contrast to experimental results obtained for compensated fMs $R\mathrm{Fe}{\mathrm{O}}_{3}\phantom{\rule{4pt}{0ex}}(R=\mathrm{Nd}$, Sm, Er) orthoferrites showing EB in a narrow range, both above and below ${T}_{\mathrm{comp}}$. We suppose that breakdown of EB in $\mathrm{GdCr}{\mathrm{O}}_{3}$ may be linked to the lack of anisotropy of the spin-only Gd $S$-ion magnetic moment dominating below ${T}_{\mathrm{comp}}$.