Crossover between universality classes in a magnetically disordered metallic wire

Abstract

In this paper, we present the numerical results of conduction in a disordered quasi-one-dimensional wire in the possible presence of magnetic impurities. Our analysis leads us to the study of universal properties in different conduction regimes, such as the localized and metallic ones. In particular, we analyze the crossover between universality classes occurring when the strength of magnetic disorder is increased. For this purpose, we use a numerical Landauer approach, and derive the scattering matrix of the wire from the electron's Green's function. t i j is the hopping term from site i to j. In the following, t i j will take two different values: t i j = t // in the longitudinal x-direction and t i j = t ⊥ in the transverse y-direction. The scalar disorder potential V = {v i } i is diagonal in electron-spin space. We choose the v i to be random scalars uniformly distributed in the interval [−W/2, W/2]. In this work, we have chosen without loss of generality to fix t // = 1 so that all energy scales are relative to the bandwidth t // = 1, and the amplitude of disorder W = 0.6. In equation (1), s, s label the SU(2) spin of electrons and the S i account for spins of the frozen magnetic impurities. A realistic choice for these frozen New Journal of Physics 14 (2012) 023026 (http://www.njp.org/) 〈 g 2 〉 c J = 0.025 J = 0.05 J = 0.075 J = 0.1 J = 0.15 J = 0.2 J = 0.3 J = 0.4 Analytical fits Quasi 1d UCF L y = 40

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