Temperature-dependent ARUPS from the heavy fermion compound CeNi2Ge2(001)

Angular resolved ultraviolet photoelectron spectroscopy is presented for th e (001) surface of the ternary heavy fermion compound CeNi2Ge2. The samples are atomically clean and well-ordered thin films grown on a W(110) substra te under UHV-condition. The temperature was varied between 10 K and 300 K. The spectra were excited by means of HeI light (hv=21.2 eV). An enhanced in tensity near the Fermi edge is observed at low temperatures for this excita tion energy. With the variation of the detection angle, not only a change o f the intensity but also of the position of the signal near the Fermi edge was observed. Furthermore the work function is drastically lowered, exhibit ing an unusually high positive temperature coefficient of about 0.65 meV/K. (C) 1999 Elsevier Science B.V. All rights reserved.