Temperature Dependence of Low-Energy Optical Conductivity of Yb4(As1-xPx)3 (x = 0, 0.05, 0.15)

Abstract

To investigate the anomalous transport property and the electronic structure near the Fermi level of Yb 4 As 3 , we measured the temperature dependence of the reflectivity spectra of Yb 4 (As 1- x P x ) 3 ( x = 0, 0.05, 0.15) in the photon energy range of 2 meV–1.5 eV. The optical conductivity spectrum due to carrier absorption (Drude curve) significantly changes with temperature. Above 200 K, the Drude curve with a high effective carrier density ( N eff ) and a short relaxation time (τ) is commonly observed in all Yb 4 (As 1- x P x ) 3 . On the other hand, below 70 K, the Drude curve changes to one with a low N eff and a long τ below 10 meV. At the same temperature, a new peak appears at 15 meV in Yb 4 As 3 . The Drude curve and the new peak are considered to originate from the bare As 4 p hole band and the hybridization state between the 4 f and 5 d bands on the Yb 3+ chain, respectively.