Thermodynamics of the anisotropic two-channel Kondo problem

Abstract

We construct and solve numerically the thermodynamic Bethe Ansatz equations for the spin-anisotropic two-channel Kondo model in arbitrary external field $h$. At high temperatures the specific heat and the susceptibility show power law dependence. For $h \to 0$ and at temperatures below the Kondo temperature $T_K$ a two-channel Kondo effect develops characterized by a Wilson ratio 8/3, and a logarithmic divergence of the susceptibility and the linear specific heat coefficient. Finite magnetic field, $h>0$ drives the system to a Fermi liquid fixed point with an unusual Wilson ratio which depends sensitively on $h$.