Publikationsdatum:
2011-04-30
Beschreibung:
Author(s): M. Wissinger, D. Fuchs, L. Dieterle, H. Leiste, R. Schneider, D. Gerthsen, and H. V. Löhneysen Thin epitaxial films of Sr_{1-x} Ca_{x} RuO_{3} on (001)-oriented SrTiO_{3} and (La_{0.3} Sr_{0.7} )(Al_{0.65} Ta_{0.35} ) 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 SrRuO_{3} 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., ∂T_{C} /∂V_{uc} ≈26.2 K/ Å^{3} , nearly independent of x. Remarkably, the biaxial epitaxial pressure leads to nearly the same value of ∂T_{C} /∂V_{uc} as deduced for bulk SrRuO_{3} 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. [Phys. Rev. B 83, 144430] Published Fri Apr 29, 2011
Schlagwort(e):
Magnetism
Print ISSN:
1098-0121
Digitale ISSN:
1095-3795
Thema:
Physik
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