Magnetic anisotropy and magnetocaloric effect in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Gd</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>NiMnO</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:mrow></mml:math> thin films
Amitava Ghosh, Roumita Roy, R. C. Sahoo, S.N. Sarangi, Mithun Ghosh, Dipak Mazumdar, D. Samal, P. S. Anil Kumar, Z. Hossain, Sudipta Kanungo, Chanchal Sow
Abstract
The magnetism and magnetocaloric effect in double perovskites is an alluring area of research due to its tunable nature. In particular, the exchange interactions and local ordering of magnetic sublattices are sensitive to the chemical substitution, synthesis/growth conditions, and strain. Here we study the effect of strain on magnetism in ${\mathrm{Gd}}_{2}{\mathrm{NiMnO}}_{6}$ double perovskite thin films grown using pulsed laser deposition on ${\mathrm{SrTiO}}_{3}$ (001) substrate. Magnetostructural study finds tensile strain to be the origin of perpendicular magnetic anisotropy in ${\mathrm{Gd}}_{2}{\mathrm{NiMnO}}_{6}$. Further, the anisotropic nature prevails in magnetocaloric effect as well. Magnetic entropy change along the in-plane direction is observed to be 21.82 J ${\mathrm{Kg}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$, which reduces to 9.84 J ${\mathrm{Kg}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ along the out-of-plane direction. Our theoretical calculation reveals a ferrimagnetic ground state of ${\mathrm{Gd}}_{2}{\mathrm{NiMnO}}_{6}$. The relative spin orientation of Ni and Mn changes from parallel configuration for strained ${\mathrm{Gd}}_{2}{\mathrm{NiMnO}}_{6}$ to antiparallel configuration for strain-relaxed ${\mathrm{Gd}}_{2}{\mathrm{NiMnO}}_{6}$.