https://doi.org/10.1140/epjb/e2005-00249-5
Transport and localisation in the presence of strong structural and spin disorder
1
Institute for Physics, Theoretical Physics III, Electronic
Correlations and Magnetism,
University of Augsburg, 86135 Augsburg, Germany
2
Harish-Chandra Research Institute,
Chhatnag Road, Jhusi, Allahabad 211 019, India
Corresponding author: a pinaki@mri.ernet.in
Received:
13
January
2005
Published online:
11
August
2005
We study a tight binding model including both on site disorder and coupling
of the electrons to randomly oriented magnetic moments. The transport properties
are calculated via the Kubo-Greenwood scheme, using the exact eigenstates of
the disordered system and large system size extrapolation of the low frequency
optical conductivity. We first benchmark our method in the model with only
structural disorder and then use it to map out the transport regimes and metal-insulator
transitions in problems involving (i) scattering from random magnetic
moments, and (ii) the combined effect of structural disorder and magnetic
scattering. We completely map out the dependence of the d.c conductivity on
electron density (n) the structural disorder and the magnetic
coupling (J'), and locate the insulator-metal phase boundary in the space of
. These results serve as a reference for understanding transport
in systems ranging from magnetic semiconductors to double exchange `colossal
magnetoresistance' systems. A brief version of this study appears in our earlier
paper Europhys. Lett. 65, 75 (2004).
PACS: 72.10.Bg – General formulation of transport theory / 72.15.Qm – Scattering mechanisms and Kondo effect / 72.15.Rn – Localization effects (Anderson or weak localization)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005