Eur. Phys. J. B 69, 465-471 (2009)
https://doi.org/10.1140/epjb/e2009-00191-6

Random field effects in field-driven quantum critical points

Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany

Corresponding author: ^a rosch@thp.uni-koeln.de

Received: 19 January 2009
Revised: 16 April 2009
Published online: 13 June 2009

Abstract

We investigate the role of disorder for field-driven quantum phase transitions of metallic antiferromagnets. For systems with sufficiently low symmetry, the combination of a uniform external field and non-magnetic impurities leads effectively to a random magnetic field which strongly modifies the behavior close to the critical point. Using perturbative renormalization group, we investigate in which regime of the phase diagram the disorder affects critical properties. In heavy fermion systems where even weak disorder can lead to strong fluctuations of the local Kondo temperature, the random field effects are especially pronounced. We study possible manifestation of random field effects in experiments and discuss in this light neutron scattering results for the field driven quantum phase transition in CeCu_5.8Au_0.2.