Temperature dependence of the Kondo resonance peak in photoemission spectra of YbCdCu4

We studied the electronic structure of YbCdCu4, which is known as a heavy fermion compound, by means of photoe- mission spectroscopy. An energy shift and an intensity enhancement of the Yb2+ 4 f7/2 peak are clearly observed with decreasing temperature. The characteristic energy scale of the Kondo temperature is estimated as ~26.5 meV, which is in agreement with the Kondo temperature obtained by the magnetic susceptibility measurements. It suggests that the observed 4 f7/2 state is associated with the heavy fermion behavior of YbCdCu4.