Upper critical magnetic field of the heavy-fermion superconductorUPt3

Abstract

The longitudinal and transverse upper critical magnetic fields $H_{c2\mathrm{}}^{\parallel }$ and $H_{c2\mathrm{}}^{\perp }$ as a function of temperature $T$ of a single-crystal specimen of the heavy-fermion superconductor ${\mathrm{UPt}}_3$ were measured resistively with the current flowing along the hexagonal $c$ axis. The slope of the linear part of the $H_{c2\mathrm{}}^{\parallel } \mathrm{}\left(T\right)\mathrm{}$ curve near the superconducting transition temperature $T_c=0.52\mathrm{}$ K equals 63 kOe/K, from which a zero-temperature superconducting coherence length ${\xi }_0\sim 120$ Å can be inferred. An analysis using previously reported specific-heat data yields an effective mass ~200 times the free-electron mass and a value of ${\xi }_0\sim 170$ Å. The electrical resistivity between $T_c$ and 8 K varies as $T^n$ with $n=1.6\mathrm{}\pm 0.1$.