Ferromagnetic-to-antiferromagnetic transition in UCu2Ge2: Magnetoresistance study.

Abstract

We report a detailed study of magnetoresistance in the intermetallic compounds ${\mathrm{UCu}}_{2}$${\mathrm{Ge}}_{2}$ and (${\mathrm{U}}_{0.95}$${\mathrm{Ce}}_{0.05}$)${\mathrm{Cu}}_{2}$${\mathrm{Ge}}_{2}$ in the temperature range of 4.5 to 140 K and in magnetic fields up to 50 kOe. The present measurements support the earlier conjecture drawn from the magnetic studies that the ferromagnetic to antiferromagnetic transition takes place gradually over a wide temperature range. The magnetic-field dependence of magnetoresistance shows that the low-temperature antiferromagnetic state is more fragile in ${\mathrm{UCu}}_{2}$${\mathrm{Ge}}_{2}$ than in (${\mathrm{U}}_{0.95}$${\mathrm{Ce}}_{0.05}$)${\mathrm{Cu}}_{2}$${\mathrm{Ge}}_{2}$.