Competing Magnetic Phases in Gd 0.5 Sm 0.5 TiO ₃ : Field‐Induced Transitions for Cryogenic Magnetocaloric Cooling

Rare‐earth titanates RTiO 3 exhibit a magnetic crossover from G‐type antiferromagnetism (G‐AFM) to ferromagnetism (FM) governed by the A‐site ionic radius. We investigate the phase‐boundary solid solution Gd 0.5 Sm 0.5 TiO 3 using density functional theory (DFT) + U calculations to analyze competing magnetic orders. Our results identify the G‐AFM configuration as the zero‐temperature DFT ground state, separated from the metastable FM state by only 13.54 meV/Ti, indicating that 50% Sm substitution drives the system into the AFM regime. Conversely, A‐type AFM and C‐type AFM configurations are dynamically unstable. Analysis of local magnetic moments reveals robust rare‐earth ferrimagnetism but highly sensitive Ti moments (0.15–0.64 ) arising from exchange frustration. The energetic proximity of the G‐AFM and FM phases suggests that field‐induced metamagnetic transitions are achievable at accessible magnetic fields (5–10 T). Thus, the Gd 1 − x Sm x TiO 3 series offers a tunable platform for optimizing magnetocaloric effects for cryogenic cooling applications.