Three-sublattice analyses on magnetic and magneto-optical properties of scandium substituted ytterbium iron garnet in high magnetic fields

A three-sublattice model is applied to study the magnetic properties of scandium substituted ytterbium iron garnet (Sc-YbIG). The magnetic moments in three magnetic sublattices (a, c and d sites) in Sc-YbIG are analyzed, where the diamagnetic Sc3+ ions substitute for octahedral Fe3+ ions. The parameters αi (i=a, c, d), associated with the exchange field and the magnetic susceptibility, are introduced. Here, αi show obvious high magnetic field-dependent and temperature-dependent properties. Based on the thought of three magnetic sublattices, the magneto-optical properties in Sc-YbIG, as magnetic field applied along [100], [110] and [111] directions, at low temperatures are studied by an improved magneto-optical four-level model, where the physical mechanism of magneto-optical anisotropy is explored in low magnetic fields. Our theory is in good agreement with the experimental results. •A three-sublattice model is applied to study the magnetic properties of Sc-YbIG.•The magneto-optical properties in Sc-YbIG are studied by an improved MO four-level model.•The physical mechanism of magnetic and magneto-optical anisotropy in Sc-YbIG is explored.•Successful fits to the experimental data are presented.