Effect of high pressure on the electrical resistivity of the heavy-fermion compound UBe13.

Abstract

The electrical resistivity \ensuremath{\rho} of the heavy-electron superconductor ${\mathrm{UBe}}_{13}$ was investigated over temperatures ranging from 1 to 300 K and at high pressures from 12 to 152 kbar. The temperature, ${\mathit{T}}_{\mathrm{max}}$, at which \ensuremath{\rho} attains a maximum increases linearly with pressure at two limiting rates: 0.25 K/kbar below \ensuremath{\sim}30 kbar and 0.65 K/kbar above \ensuremath{\sim}30 kbar. At low temperatures, the \ensuremath{\rho}-versus-T data can be described by the expression \ensuremath{\rho}=${\mathrm{\ensuremath{\rho}}}_{0}$+${\mathit{AT}}^{2}$ over a temperature interval of \ensuremath{\sim}1 K at 12 kbar to more than 16 K at 152 kbar. The coefficient A can be related to the Fermi-liquid energy scale ${\mathit{T}}^{\mathrm{*}}$ by ${\mathit{A}}^{\mathrm{\ensuremath{-}}1/2}$\ensuremath{\propto}${\mathit{T}}^{\mathrm{*}}$. The pressure dependence of ${\mathit{A}}^{\mathrm{\ensuremath{-}}1/2}$ also increases linearly with pressure at two limiting rates, with a crossover at about 50 kbar. The similarity in the pressure dependences of ${\mathit{T}}_{\mathrm{max}}$ and ${\mathit{A}}^{\mathrm{\ensuremath{-}}1/2}$ suggests that both parameters are proportional to a single energy scale, while the changes in pressure dependence of ${\mathit{T}}_{\mathrm{max}}$ and ${\mathit{A}}^{\mathrm{\ensuremath{-}}1/2}$ may represent a crossover from heavy-fermion to intermediate-valence behavior.