Structural role in temperature-induced magnetization reversal revealed in distorted perovskite Gd1–xYxCrO3

The phenomenon of temperature induced magnetization-reversal, giving rise to negative magnetization (NM) in several rare-earth chromates, has been revisited through magnetization studies on $\mathrm{G}{\mathrm{d}}_{1\ensuremath{-}x}{\mathrm{Y}}_x\mathrm{Cr}{\mathrm{O}}₃$. The study re-examines the well accepted explanation of NM, i.e., the antiparallel polarization of the paramagnetic rare-earth $({\mathrm{R}}³⁺)$ moments against the weak magnetization $({M}_{\mathrm{Cr}})$ of the canted antiferromagnetically ordered $\mathrm{C}{\mathrm{r}}³⁺$ moment subsystem and compares the results with a relatively new explanation invoking frustration of the $\mathrm{G}{\mathrm{d}}³⁺$ moment subsystem at temperatures as high as 170 K [Phys. Rev. B 99, 014422 (2019)]. Keeping in view the highly localized nature of f electrons the invoked frustration appears unphysical. We find that the magnitude of the NM increases with increasing concentration of nonmagnetic ${\mathrm{Y}}³⁺$ ion. This is attributed to increased antiparallel polarization of the $\mathrm{G}{\mathrm{d}}³⁺$ moments against increased ${M}_{\mathrm{Cr}}$ due to structural modifications in $\mathrm{G}{\mathrm{d}}_{1\ensuremath{-}x}{\mathrm{Y}}_x\mathrm{Cr}{\mathrm{O}}₃$ with increasing ${\mathrm{Y}}³⁺$ content. This observation strongly contradicts the interpretation for NM based on the frustration of $\mathrm{G}{\mathrm{d}}³⁺$ moments. The temperature induced negative to positive magnetization jump (TMJ) is observed and is attributed to the minimization of the Zeeman-energy against an energy barrier. A phenomenological comparative study of the modified Curie-Weiss fitting to M($T$) indicates that TMJ in polycrystalline $\mathrm{G}{\mathrm{d}}_{1\ensuremath{-}x}{\mathrm{Y}}_x\mathrm{Cr}{\mathrm{O}}₃$ is an outcome of cascaded individual flips of $\mathrm{G}{\mathrm{d}}³⁺$ moments occurring over random sites having homogeneously distributed barrier energy. In our analysis the M($T$) data is fitted using modified Curie-Weiss treating ${M}_{\mathrm{Cr}}$ to be temperature dependent, i.e., ${M}_{\mathrm{Cr}}(T)=M(0)$.${[1\ensuremath{-}{(T/{T}_C)}^{\ensuremath{\alpha}}]}^{\ensuremath{\beta}}$.