Magnetic properties of strain-controlled SrRuO3 thin films

Coherently-grown heteroepitaxial oxide thin films on single crystal substrates are always under elastic strain. This strain causes changes in the physical properties of thin films. We have studied the behavior of anisotropic magnetic properties of SrRuO3 films grown directly on SrTiO3 and on Ba1-xSrTiO3/BaTiO3 bilayer buffer layers. The in-plane lattice constant of the buffer layer was adjusted between 3.91 and 3.99 Angstrom by changing the Ba/Sr ratio in the Ba1-xSrxTiO3 layer. It was found that the easy axis of magnetization is perpendicular to the surface in compressively strained films and rotates into the in-plane direction in strain-free films. Tensile strain was found to increase the ferromagnetic ordering temperature of SrRuO3 from 160 K to 164 K.