Role of disorder on the quantum critical point of a model for heavy fermions (original) (raw)

A zero temperature real space renormalization group (RG) approach is used to investigate the role of disorder near the quantum critical point (QCP) of a Kondo necklace (XY-KN) model. In the pure case this approach yields Jc = 0 implying that any coupling J = 0 between the local moments and the conduction electrons leads to a non-magnetic phase. We also consider an anisotropic version of the model (X − KN), for which there is a quantum phase transition at a finite value of the ratio between the coupling and the bandwidth, (J/W). Disorder is introduced either in the onsite interactions or in the hopping terms. We find that in both cases randomness is irrelevant in the X − KN model, i.e., the disorder induced magnetic-non-magnetic quantum phase transition is controlled by the same exponents of the pure case. Finally, we show the fixed point distributions PJ (J/W) at the atractors of the disordered, non-magnetic phases.