Time-resolved optical spectroscopy of the itinerant antiferromagnets UMGa$_{5}$ (M=Ni, Pt)

ORAL

Abstract

We present time-resolved optical conductivity measurements of the itinerant antiferromagnets UNiGa$_{5}$ ($T_{N}$=85K) and UPtGa$_{5}$ ($T_{N}$=25K), as well as the parent material UGa$_{3}$, using a pump-probe technique. The relaxation time $\tau$ diverges near $T_{N}$, which we attribute to the opening of a spin gap. $\tau$ also diverges at the lowest temperatures, 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 exhibits a sign change at $T_{N}$, whose temperature dependence is also consistent with the appearance of a spin gap. We will also attempt to analyze our data using the Rothwarf-Taylor model.

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Authors

  • Ee Min Elbert Chia

  • Hae Ja Lee

    • MST-CINT, Los Alamos National Laboratory

  • Ed Bauer

    • LANL
    • Los Alamos National Laboratory

  • N. Hur

    • Los Alamos National Lab, Cond. Matt. and Thermal Physics
    • MST-10, Los Alamos National Laboratory

  • Richard Averitt

    • Los Alamos National Laboratory
    • Los Alamos National Lab

  • Antoinette Taylor

    • Los Alamos National Laboratory
    • MST-CINT, Los Alamos National Laboratory

  • John Sarrao

    • LANL, USA
    • MST-10, Los Alamos National Laboratory