Strong correlation between anomalous quasiparticle scattering and unconventional superconductivity in the hidden-order phase of URu 2Si 2

The pressure dependent electrical resistivity of URu 2Si 2 has been studied at high pressure across the first order phase boundary of P x where the ground state switches under pressure from "hidden order" (HO) to large moment antiferromagnetic (LAFM) states. The electrical transport in URu 2Si 2 at low temperatures shows a strong sample dependence. We have measured an ultraclean single crystal whose quality is the highest among those used in previous studies. The generalized power law ρ=ρ 0+A nTn analysis finds that the electric transport property deviates from Fermi liquid theory in the HO phase but obeys the theory well above P x. The analysis using the polynomial in T expression ρ= ρ 0+α 1T+α 2T2 reveals the relation α 1/α 2 T sc in the HO phase. While the pressure dependence of α 2 is very weak, α 1 is roughly proportional to T sc. This suggests a strong correlation between the anomalous quasiparticle scattering and the superconductivity and that both have a common origin. The present study clarifies a universality of the HO phase inherent in strongly correlated electron superconductors near quantum criticality. © 2012 American Physical Society