Photoemission Spectroscopy Study on the Heavy-Fermion Compound YbAgCu<sub>4</sub>

Anzai, H.; Tawara, Ryoga; Kikuchi, Yoshiyuki; Sato, Hitoshi; Arita, Masashi; Takaaze, Ren; Matsumoto, Kunihiro; Hiraoka, Koichi

doi:10.7566/jpsj.91.114703

Cited by 2 publications

(1 citation statement)

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“…4d, e . The peak position shifts from 42 meV to 22 meV with decreasing temperature and is saturated at 30 K. The integrated intensity increases with decreasing temperature and is also saturated at 30 K. According to photoelectron spectroscopic studies of bulk RE intermetallic compounds, such saturated temperature represents a coherence temperature ( T c o h ), at which the c - f hybridization state is fully established, resulting in a HF state 38 , 39 . T c o h sets the temperature scale on which the weight increases and saturation typically occurs below T c o h .…”

Section: Resultsmentioning

confidence: 99%

Two-dimensional heavy fermion in a monoatomic-layer Kondo lattice YbCu2

Nakamura,

Sugihara,

Chen

et al. 2023

Nat Commun

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The Kondo effect between localized f-electrons and conductive carriers leads to exotic physical phenomena. Among them, heavy-fermion (HF) systems, in which massive effective carriers appear due to the Kondo effect, have fascinated many researchers. Dimensionality is also an important characteristic of the HF system, especially because it is strongly related to quantum criticality. However, the realization of the perfect two-dimensional (2D) HF materials is still a challenging topic. Here, we report the surface electronic structure of the monoatomic-layer Kondo lattice YbCu2 on a Cu(111) surface observed by synchrotron-based angle-resolved photoemission spectroscopy. The 2D conducting band and the Yb 4f state, located very close to the Fermi level, are observed. These bands are hybridized at low-temperature, forming the 2D HF state, with an evaluated coherence temperature of about 30 K. The effective mass of the 2D state is enhanced by a factor of 100 by the development of the HF state. Furthermore, clear evidence of the hybridization gap formation in the temperature dependence of the Kondo-resonance peak has been observed below the coherence temperature. Our study provides a new candidate as an ideal 2D HF material for understanding the Kondo effect at low dimensions.

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Section: Resultsmentioning

confidence: 99%