Temperature-Dependent Change of Correlated Electronic States in Yb4As3and Yb4(As1-xSbx)3Probed by High Resolution Photoemission Spectroscopy

Clear changes of the Yb 4f photoemission spectra with temperature are observed in Yb 4 As 3 by high resolution photoemission spectroscopy. The photoemission intensity is very low at the Fermi level and decreases as the temperature is lowered in accord with the narrowing of the 4f spectra. Bulk and surface contributions are deconvoluted in the 4f 13 final state spectra. In comparison with the corresponding results in Yb 4 (As 1- x Sb x ) 3 , the spectral changes of Yb 4 As 3 with temperature are confirmed to be beyond simple thermal broadening effects and related to the charge ordering effects. Although the change from the charge ordering temperature ( T t ) down to about T t /2 is consistent with a theoretical prediction, the change below it is rather unusual and may be ascribed to the incompleteness of the charge ordering effect. Spectral changes with Yb 4 Sb 3 -substitution are qualitatively discussed.