We report the emergence of bulk superconductivity in Au64.0Ge22.0Yb14.0 and Au63.5Ge20.5Yb16.0 below 0.68 and 0.36 K, respectively. This is the first observation of superconductivity in Tsai-type crystalline approximants of quasicrystals. The Tsai-type cluster center is occupied by Au and Ge ions in the former approximant, and by an Yb ion in the latter. For magnetism, the latter system shows a larger magnetization than the former. To explain this observation, we propose a model that the cluster-center Yb ion is magnetic. The relationship between the magnetism and the superconductivity is also discussed.
@article{arxiv.1501.01719,
title = {Superconductivity of Au-Ge-Yb Approximants with Tsai-Type Clusters},
author = {Kazuhiko Deguchi and Mika Nakayama and Shuya Matsukawa and Keiichiro Imura and Katsumasa Tanaka and Tsutomu Ishimasa and Noriaki K. Sato},
journal= {arXiv preprint arXiv:1501.01719},
year = {2015}
}