Cluster Glass Behavior in Orthorhombic SmFeO₃ Perovskite: Interplay between Spin Ordering and Lattice Dynamics

In this report, the isothermal time-dependent Raman scattering study has been used to investigate the origin of the cluster glass state in samarium orthoferrites (SmFeO3) via probing selective dynamics of different magnetic sublattices in the time domain. The existence of a cluster glass state in multiferroic SmFeO3 was demonstrated using direct current, alternating current, and field-dependent magnetic measurements. The temperature-dependent X-ray diffraction measurement confirms an anomaly in various structural parameters such as in the lattice constants, full width at half-maximum of X-ray diffraction peak, Fe/Sm–O bond lengths, and Fe/Sm–O–Fe bond angles across the cluster glass temperature regions; which suggest spin–lattice coupling in the SmFeO3 system. Further, the existence of a strong spin–lattice and magnetoelastic coupling has been confirmed using temperature-dependent Raman scattering investigation of the SmFeO3 sample. Moreover, the relaxation dynamics of sublattices of magnetic ions (Sm, Fe) in SmFeO3 across the cluster glass region were investigated using the isothermal time-dependent Raman scattering study, which evidently indicates the metastable state in the glassy region, whereas the said metastability is found to be completely absent beyond the glassy region.