Strain control of phase transition and magnetocaloric effect in Nd_0.5Sr_0.5MnO₃ thin films

Phase transition and the magnetocaloric effect (MCE) in Nd_0.5Sr_0.5MnO₃ (NSMO) epitaxial thin films were tailored through controlling the lattice-mismatch-induced-strain by depositing on (011) - (La_0.18Sr_0.82)(Al_0.59Ta_0.41)O₃ and SrTiO₃ (STO) single crystalline substrates, respectively. The NSMO film grown on STO, exhibiting uniaxial like tensile strain of 1.3% along the in-plane [100] direction, undergoes a paramagnetic to ferromagnetic transition at ∼210 K followed by a ferromagnetic to A-type antiferromagnetic transition at ∼179 K upon cooling; meanwhile, the film grown on LSAT, exhibiting anisotropic in-plane tensile strains of 0.36% along [100] and 0.50% along [0 1 ̄ 1] directions, undergoes further transition to CE-type antiferromagnetic transition at ∼145 K. NSMO/LSAT with such transitions facilitates a strong MCE over a much wider temperature range from 90 to 170 K, with the magnetic entropy change comparable to the recently reported La_0.25Ca_0.75MnO₃ bulk. These findings suggest that control of strain in manganite films with first-order phase transition is a feasible way to broaden their MCE temperature range.