Ultrafast Dynamics of the Itinerant Antiferromagnet UNiGa_5

摘要

Time-resolved photoinduced reflectivity data were measured for the itinerant antiferromagnet UNiGa_5 (T_N ≈ 85 K) from room temperature down to 10 K. The relaxation time τ increases sharply near T_N, which we attribute to the opening of a spin gap. In addition, at the lowest temperatures τ increases with a T~1 dependence, which is similar to that shown by the heavy fermion YbAgCu_4, but with no blocking of electron-phonon scattering within the DOS peak. The transient amplitude increase at T_N with a temperature dependence that is consistent with the appearance of a spin gap.