title: Fermi-surface reconstruction without breakdown of Kondo screening at the quantum critical point.
abstract: Motivated by recent Hall-effect experiment in YbRh(2)Si(2), we study ground state properties of a Kondo lattice model in a two-dimensional square lattice using variational Monte Carlo method. We show that there are two types of phase transition, an antiferromagnetic transition and a topological one (Fermi-surface reconstruction). In a wide region of parameters, these two transitions occur simultaneously without the breakdown of Kondo screening, accompanied by a discontinuous change of the Hall coefficient. This result is consistent with the experiment and gives a novel theoretical picture for the quantum critical point in heavy-fermion systems.
authors.affiliation: Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. hwatanabe@hosi.phys.s.u-tokyo.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watanabe
authors.forename: Masao
authors.initials: M
authors.lastname: Ogata