Non-local correlation effects and metal-insulator transition in the s-d exchange model
J. Sweep, A. N. Rubtsov+, M. I. Katsnelson
Radboud University Nijmegen, Institute for Molecules and Materials, NL-6525AJ Nijmegen, The Netherlands
+Department of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
Abstract
The metal-insulator transition within the s-d exchange model is studied by the
Dynamical Mean Field Theory and Dual Fermion approaches. The latter takes into
account nonlocal correlation effects which are shown to be essential. In particular, the
critical values of the s-d exchange coupling constant for these two methods turn out to be
different by a factor of more than two (for the case of square lattice and spin 1/2 localized
electrons). The calculations were performed using a Continuous-Time Quantum Monte
Carlo method. The difference of the quantum spin-1/2 case and the classical-spin case is
discussed. For the quantum case the sign of s-d exchange coupling constant is relevant
which demonstrates an importance of the Kondo effect.