We have measured susceptibility, specific heat, resistivity, and thermopower of CaCu3Ti4−xRuxO12 and CaCu3−yMnyRu4O12, and have found that CaCu3Ru4O12 can be regarded as a heavy-fermion oxide in d-electron systems. The Kondo temperature is near 200 K, and the susceptibility (1.4×10−3 emu/Cu mol) and the electron specific heat coefficient (28 mJ/Cu molK2) are moderately enhanced. The resistivity is proportional to T2 at low temperatures, and satisfies the Kadowaki-Woods relation. The heavy-fermion state comes from the interaction between the localized moment of Cu 3d and the conduction electron of Ru 4d. An insulator-metal transition occurs between x=1.5 and 4 in CaCu3Ti4−xRuxO12, which can be regarded as a transition from magnetic insulator to heavy-fermion metal.
@article{arxiv.cond-mat/0404247,
title = {A novel heavy-fermion state in CaCu_3Ru_4O12},
author = {W. Kobayashi and I. Terasaki and J. Takeya and I. Tsukada and Yoichi Ando},
journal= {arXiv preprint arXiv:cond-mat/0404247},
year = {2009}
}
Comments
4 pages, 5 figures, submitted to J. Phys. Soc. Jpn