Anomalous Pressure Dependence of KadowakiWoods ratio and Crystal Field Effects in Mixedva.pdf

Anomalous Pressure Dependence of Kadowaki-Woods Ratio and Crystal Field Effects in Mixed-Valence YbInCu4 1 1 ∗ 1 1 Tuson Park , V. A. Sidorov , J. L. Sarrao , and J. D. Thompson 1Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA (Dated: February 2, 2008) The mixed-valence (MV) compound YbInCu4 was investigated by electrical resistivity and ac 6 specific heat at low temperatures and high pressures. At atmospheric pressure, its Kadowaki- 0 Woods (KW) ratio, A/γ2 , is 16 times smaller than the universal value RKW (= 1.0 × 0 −5 2 2 −2 2 10 µΩ·cm·mol ·K ·mJ ), but sharply increases to 16.5RKW at 27 kbar. The pressure-induced change in the KW ratio and deviation from RKW are analyzed in terms of the change in f-orbital r degeneracy N and carrier density n. This analysis is further supported by a dramatic change in a M residual resistivity ρ0 near 25 kbar, where ρ0 jumps by a factor of 7. 4 At low temperatures, strongly correlated metals ex- at P = 27 kbar and show that the pressure dependence ] hibit an enhanced electronic specific heat that is a mea- of the KW ratio and deviation from RKW are due to l sure of the density of electronic states at the Fermi en- the change in f-orbital degeneracy N and carrier density e - ergy N (EF), which results from hybridization of nearly- n. This c