Deviation from Matthiessen rule in magnetic disordered alloys–theoretical investigation

The model of the magnetic disordered alloys, including the itinerant electrons, localized spins and phonons, was elaborated in details in the paramagnetic region with the use of the Coherent Potential Approximation (CPA) approach. The expression for the DC electrical conductivity was taken from the Kubo-Greenwood formula for an alloys. The separate (residual, phonon and magnetic) contributions to the resistivity for the temperatures above Curie transition temperature, different sets of the model parameters were calculated. The linear temperature dependence of the phonon contribution to the resistivity was reproduced except from the anomalous behavior observed for the parameters sets for which the Fermi level locates near the band's edges. For the same parameters sets our calculations showed the largest percentage deviations from the Matthiessen's rule. Our model calculations confirmed the Matthiessen's rule generalized to the case of the three, residual, phonon and magnetic contributions to the resistivity of the magnetic disordered alloys with the partially filled band when the Fermi level locates far from the bands edges. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)