HiSORセミナー
Two-dimensional heavy fermion in a monoatomic-layer Kondo lattice YbCu2
日時 2023年11月8日 （水） 16：30～17：45
場所 広島大学放射光科学研究センター 2階 セミナー室
講師 Shin-ichi Kimura
(Osaka University and Institute for Molecular Science, Japan)
The dimensionality is an important parameter for tuning physical properties in strongly correlated electron systems [1]. Even in heavy fermions (HFs), tuning the dimensionality is a challenging issue because of the intermetallic compounds. So far, some trials to fabricate atomic layered heavy fermion have been performed, one is the superlattice heterostructure of CeIn3 and LaIn3 fabricated by a molecular-beam epitaxy method [2]. With decreasing thickness, the coherent temperature Tcoh, which is a mark of the Kondo effect, shifts to the low-temperature side, suggesting the closing to the quantum critical point. Here, we introduce our recent trial to establish mono-atomic layered HFs in YbM2 (M: Cu, Ag, Au). Among YbM2, the mono-atomic layered YbCu2 on a Cu(111) surface shows a HF character in the electronic structure with synchrotron-based angle-resolved photoelectron spectroscopy [3]. The two-dimensional (2D) conduction band and the Yb 4f state are observed near the Fermi level. These bands are hybridized at lower temperatures than ~100 K, forming a 2D HF state, with an evaluated Tcoh of about 30 K. Furthermore, clear evidence of the hybridization gap formation in the temperature dependence of the Kondo-resonance peak has been observed below Tcoh. These results strongly suggest that YbCu2 on Cu(111) is a monoatomic layered HF material.
[1] S. Sachdev, Science 288, 475 (2000).
[2] H. Shishido et al., Science 327, 980 (2010).
[3] T. Nakamura, sk et al., arXiv: 2306.06984.
問合せ先 出田真一郎（放射光科学研究センター）
