Influence of substrate induced strain on B-site ordering and magnetic properties of Nd2NiMnO6 epitaxial thin films

Epitaxial thin films of double perovskite Nd2NiMnO6 (NNMO) have been successfully grown on (001) oriented substrates of (LaAlO3)0.3-(Sr2AlTaO6)0.7 (LSAT), SrTiO3 (STO) and LaAlO3 (LAO) by pulsed laser deposition under optimum growth conditions. X-Ray diffraction and reciprocal space maps of the asymmetric (103) peak reveal that the films deposited on LSAT and STO substrates are fully relaxed, while a large in- plane compressive strain has been observed in film grown on LAO. This results into the coexistence of anti-site disorder and orthorhombic phase in the film deposited on LAO, which is further confirmed from observed shift and broadening in the antisymmetric vibrations in the Raman spectra. The temperature dependent magnetization shows a ferromagnetic transition close to 200 K in all the three samples. However, film grown on LAO substrate shows an additional upturn transition at ~ 96 K (T′), which could be ascribed to the formation of antisite disorders further responsible for reduction of saturation magnetization (~ 1.8 × 105 A/m) in hysteresis curve of the sample. The ordered structure obtained on LSAT and STO exhibit in-plane easy axis with a large coercivity of ~ 0.2 T, while, the film deposited on LAO does not show any preferred anisotropic direction.