Strain-Induced First-Order Magnetic Phase Transition in Epitaxial Sm_0.35Pr_0.15Sr_0.5MnO₃ Thin Film

Abstract

Epitaxial Sm_0.35Pr_0.15Sr_0.5MnO₃ thin films were deposited on LaAlO₃ (LAO, (001)), SrTiO₃ (STO, (001)), and (La_0.18Sr_0.82)(Al_0.59Ta_0.41)O₃ (LSAT, (001)) single-crystalline substrates by using pulsed laser deposition technique. In order to examine the strain effect on electronic and magnetic properties, films were studied by X-ray diffraction, electrical resistivity, and dc magnetization measurements. The film grown on LAO substrate is under compressive strain, and it undergoes ferromagnetic → paramagnetic transition at Curie temperature (T _C) of ∼ 165 K and metal → insulator transition at ∼ 107 K. The films grown on STO and LSAT substrates are under tensile strain and have T _C of ∼ 120 and 130 K, respectively, and show metal → insulator transition at ∼ 145 and 137 K, respectively. At T < T _C, the zerofield and fieldcooled magnetization curves of all the films show a huge bifurcation. In the case of films on STO and LSAT substrates, hysteresis is also observed in fieldcooled cooling and warming magnetization vs. temperature measurement protocols at low magnetic field. All the signatures of the firstorder magnetic phase transition are absent in the case of film on LAO substrate. The occurrence and absence of firstorder magnetic phase transition in films on LAO, STO, and LSAT substrates, respectively, have been well explained through the substrateinduced film lattice strain.