Observation of High-Field Superconductivity of a Strongly Interacting Fermi Liquid inU6Fe

Measurements of the temperature dependences of the upper critical field $H_{c2\mathrm{}}$ and heat capacity $C_P$ of ${\mathrm{U}}_6$Fe are reported. $H_{c2\mathrm{}}$ increases very rapidly for a low-transition-temperature ($T_c=3.8\mathrm{}$ K) superconductor, reaching $H_{c2\mathrm{}}=64\mathrm{}$ kOe at $T=1.95\mathrm{}$ K. $C_P$ data indicate that ${\mathrm{U}}_6$Fe is a strong-coupled bulk superconductor and an exchange-enhanced paramagnet with an electronic coefficient $\gamma =145\mathrm{}\pm 10$ mJ/mole.${\mathrm{K}}^2$. ${\mathrm{U}}_6$Fe constitutes a metallurgically clean and conclusive example of the occurrence of high-field superconductivity in a strongly interacting Fermi liquid.