Anisotropic lattice changes and ferromagnetic order in Sr1-xCaxRuO3

作者：Wissinger M^*; Fuchs D; Dieterle L; Leiste H; Schneider R; Gerthsen D; Loehneysen H V

来源：Physical Review B, 2011, 83(14): 144430.

DOI：10.1103/PhysRevB.83.144430

Thin epitaxial films of Sr1-xCaxRuO3 on (001)-oriented SrTiO3 and (La0.3Sr0.7)(Al0.65Ta0.35) O-3 single-crystal substrates experience coherent compressive strain for x < 0.5 and 0.9, respectively, resulting in a nearly tetragonal structure. The tetragonal distortion c/a increases for SrRuO3 films (x = 0) up to 2.4% with respect to the pseudocubic structure of the corresponding bulk material. Increasing compressive strain leads, independently of the degree of Ca substitution, to a successive shrinkage of the unit-cell volume. For constant x, films under compressive (tensile) strain show a decrease (increase) of the ferromagnetic Curie temperature T-C compared to the bulk value. The change of T-C is found to be strongly correlated to the decrease of the unit-cell volume V-uc, i.e.,. partial derivative T-C/partial derivative V-uc approximate to 26.2 K/angstrom(3), nearly independent of x. Remarkably, the biaxial epitaxial pressure leads to nearly the same value of partial derivative T-C/partial derivative V-uc as deduced for bulk SrRuO3 under isotropic hydrostatic pressure. In view of the strong magnetic anisotropy present in the tetragonally distorted thin films, where compressive strain enhances the out-of-plane magnetization significantly, this is a rather surprising result. For moderate epitaxial strain the tetragonal distortion seems to play only a minor role for the reduced T-C in thin films.

• 出版日期2011-4-29