Effect of cationic disorder on the spin polarization in FeMo double perovskitesB. Aguilar1, O. Navarro2 and M. Avignon3
1 Laboratorio Interinstitucional de Magnetismo Natural, Instituto de Geofísica, Sede Michoacán, Universidad Nacional Autónoma de México - Morelia, México
2 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México - Apartado Postal 70-360, 04510 México D. F., México
3 Institut Néel, CNRS and Université Joseph Fourier - BP 166, 38042 Grenoble Cedex 9, France, EU
received 28 August 2009; accepted in final form 20 November 2009; published December 2009
published online 22 December 2009
Ordered Sr2FeMoO6 is expected to have complete spin polarization, however all samples usually present some degree of Fe/Mo disorder which reduces the tunneling magnetoresistance in granular samples. It can be inferred that disorder is detrimental to the half-metallicity. We present an electronic approach of this disorder using a model based on a correlated electron picture with localized Fe-spins and conduction electrons interacting with the local spins via a double-exchange–type mechanism. This succeeds in stabilizing a ferromagnetic ground state in the absence of disorder. Disorder is treated within the dynamical mean-field approach which is equivalent to the coherent potential approximation. We shall show how electron disorder affects the density of states and the ground-state properties with a particular emphasis on the spin polarization.
72.25.-b - Spin polarized transport.
71.27.+a - Strongly correlated electron systems; heavy fermions.
71.30.+h - Metal-insulator transitions and other electronic transitions.
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