Common exchange-biased spin switching mechanism in orthoferrites

Abstract

The unconventional exchange-bias (EB) effect in single crystals of $R\mathrm{Fe}{\mathrm{O}}_{3}(R=\mathrm{Nd},\phantom{\rule{0.28em}{0ex}}\mathrm{Sm})$ compensated ferrimagnets (fMs), composed of two antiferromagnetically (AFM) coupled $R$ and Fe sublattices with opposite ferromagnetic (FM) moments, exhibiting the FM moment reversal via a fast spin switching is reported. In ${\mathrm{NdFeO}}_{3}$, the EB anisotropy field emerges and diverges upon approaching the compensation temperature ${T}_{\mathrm{comp}}^{\mathrm{Nd}}=9.2\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, and changes sign with crossing ${T}_{\mathrm{comp}}^{\mathrm{Nd}}$, in similarity to the behavior observed recently in ${\mathrm{ErFeO}}_{3}$. In contrast, ${\mathrm{SmFeO}}_{3}$ exhibits a substantial EB, not only at its ${T}_{\mathrm{comp}}^{\mathrm{Sm}}=4.8\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, but also at higher temperatures up to 100 K, and the EB changes its sign with increasing cooling field. It is shown that in all known $R{\mathrm{FeO}}_{3}$ ($R=\mathrm{Nd},\phantom{\rule{0.28em}{0ex}}\mathrm{Sm},\phantom{\rule{0.28em}{0ex}}\mathrm{Er}$) compensated fMs the field-induced FM moment reversal is similarly exchange biased near ${T}_{\mathrm{comp}}$.