Stability of the fixed point of the two-channel Kondo Hamiltonian

We have performed full-scale numerical-renormalization-group calculations on the anisotropic, two-channel, impurity spin s=1/2 Kondo Hamiltonian. To allow for anisotropy we have worked in a basis of total axial charge jₐ and jb (a and b index the channels) as well as total Sz. In the isotropic limit, our results agree well with the previous work of Cragg, Lloyd, and Nozieres. The most important results are (1) confirmation of the approach to a nontrivial fixed point from weak coupling, (2) the stability of the fixed point against exchange anisotropy, and (3) the destabilization of the fixed point by the application of a magnetic field or the lifting of exchange symmetry between two channels. We find the crossover temperature scales with the square of the exchange splitting.