Spin reorientation to a Γ3(Cx, Fy, Az) …

An unusual temperature-induced spin reorientation transition from ${\mathrm{\ensuremath{\Gamma}}}_{2}({F}_{x}, {C}_{y}, {G}_{z})\ensuremath{-}{\mathrm{\ensuremath{\Gamma}}}_{23}\ensuremath{-}{\mathrm{\ensuremath{\Gamma}}}_{3}({C}_{x}, {F}_{y}, {A}_{z})$ in orthoferrite ${\mathrm{Sm}}_{0.5}{\mathrm{Y}}_{0.5}{\mathrm{FeO}}_{3}$ is observed in the range 282--312 K through magnetic susceptibility measured on oriented single crystals. The ${\mathrm{\ensuremath{\Gamma}}}_{2}\ensuremath{-}{\mathrm{\ensuremath{\Gamma}}}_{23}\ensuremath{-}{\mathrm{\ensuremath{\Gamma}}}_{3}$ transition is distinctly different from the spin configurations commonly observed in $R{\mathrm{FeO}}_{3}$ orthoferrites, and we corroborate the finding with results from Raman spectroscopic investigations. Observation of magnon spectra and the vivid correlation between spin reorientation and changes in ${B}_{2g}$ and ${B}_{3g}$ phonon modes unveil strong spin-phonon coupling prevalent in ${\mathrm{Sm}}_{0.5}{\mathrm{Y}}_{0.5}{\mathrm{FeO}}_{3}$ crystal.