Photoemission study on YbZn1-xSnxCu4

We have investigated the electronic structure of YbZn1-xSnxCu4 with x = 0.5 by means of hard x-ray photoemission spectroscopy (HAXPES) with hv = 5.95 keV and low photon energy photoemission spectroscopy (LEPES) with hv = 14 eV. The Yb valence derived from the Yb 3d HAXPES spectrum remarkably decreases between 100 and 20 K; ~ 2.90 at 300 – 100 K and 2.78 at 20 K. The LEPES spectra exhibit a prominent peak near the Fermi level which is attributed to the Kondo resonance peak. The Kondo temperature is estimated to be TK ~ 210 K from an energy position of the peak extrapolated to zero temperature.