Temperature-driven spin switching and exchange bias in the ErFeO3 ferrimagnet

Abstract

The compensated ferrimagnet orthoferrite $\mathrm{ErFe}{\mathrm{O}}_{3}$ exhibits the exchange bias (EB) effect, which was previously detected as the traditional shift of the magnetization hysteresis loops $M$ vs $H$ near the compensation temperature ${T}_{\mathrm{comp}}=45\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. This paper shows that another specific phenomenon, temperature-driven spin switching and exchange bias, occurs in this ferrimagnet. Namely, the EB manifests itself as the temperature shift of the hysteresis loops $M$ vs $T$, which occurs upon successive cooling and heating in a weak magnetic field. The $M$ vs $T$ loops limiting the region of coexistence of negative and positive magnetization are shifted towards lower or higher temperatures, depending on the sign of the applied magnetic field, which causes the unidirectional EB anisotropy. The EB anisotropy energy, which contributes to the energy barrier for switching spins to an equilibrium state, determines the shift in the switching temperature ${T}_{\mathrm{sw}}$. Exchange-biased spin switching in $\mathrm{ErFe}{\mathrm{O}}_{3}$ is discussed within a model, which explains the magnetic compensation of the canted ferromagnetic moment of the ${\mathrm{Fe}}^{3+}$ spins and the opposite moment of paramagnetic ${\mathrm{Er}}^{3+}$ spins induced by the antiferromagnetic exchange interaction between the Er and Fe ions.