Dresden 2017 – scientific programme

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MA: Fachverband Magnetismus

MA 60: Magnetic Materials: Applications and Multielement Bulk Materials

MA 60.2: Talk

Friday, March 24, 2017, 09:45–10:00, HSZ 101

Valence state of Sm in Sm-substituted EuO — Andreas Reisner, Steffen Wirth, •Simone G. Altendorf, and Liu Hao Tjeng — Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany

Europium monoxide is a ferromagnetic semiconductor with a Curie temperature of 69 K. It has the rocksalt crystal structure with a lattice constant of 5.14 Å and the Eu is in the stable high-spin divalent state. SmO on the other hand, is a non-magnetic metallic oxide. It has also the rocksalt crystal structure and the lattice constant is 4.94 Å. Interestingly, the Sm is presumably in a mix-valent state (2.9+) as argued from lattice constant considerations [J. M. Leger et al., Inorg. Chem. 19, 2252 (1980); G. Krill et al. Solid State Commun. 33, 351 (1980)]. The question now arises what the valence of the Sm will be if it is inserted in the EuO crystal. Considering the larger lattice constant of EuO as compared to SmO, one may expect that the Sm in EuO will have enough room to stabilize even the divalent (and non-magnetic) charge state [D. Kasinathan et al., Phys. Rev. B 91, 195127 (2015)].

We have grown thin films of Sm_xEu_1−xO using reactive molecular beam epitaxy. Structural analysis verifies the incorporation of Sm into the EuO crystal up to high doping levels of 17 at.%. We will present our in situ x-ray photoelectron spectroscopy study as well as our ex situ magnetization measurements to unveil the valence of Sm inserted in EuO.