Eur. Phys. J. B 84, 53-58 (2011)
https://doi.org/10.1140/epjb/e2011-20647-2

Regular Article

Magnetic properties of the ordered and disordered double perovskite Sr₂Fe_1+xMo_1−xO₆ (−1 ≤ x ≤ 1/3)

¹ Institut Néel, CNRS and Université Joseph Fourier - BP 166, 38042 Grenoble Cedex 9, France
² Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México - Apartado Postal 70-360, 04510 México D. F., México
³ Centro de Investigación en Materiales Avanzados, S. C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, 31109 Chihuahua Chih., México

^a e-mail: jaimeunam@gmail.com

Received: 7 August 2011
Received in final form: 27 September 2011
Published online: 3 November 2011

Abstract

We have studied the effect of cationic disorder on the spin polarization of the double perovskite system Sr₂Fe_1+xMo_1−xO₆ with  −1 ≤ x ≤ 1/3. The composition x = 0 corresponds to the well-known double-perovskite Sr₂FeMoO₆, which is expected to have complete spin polarization, however all samples present some degree of Fe/Mo disorder which reduces the tunneling magnetoresistance in granular samples. We consider an electronic model within the renormalized perturbation expansion Green’s functions, consisting in a correlated electron picture with localized Fe-ions and itinerant electrons interacting with the local spins via a double-exchange type mechanism. Our results show the influence of disorder on the density of states and the ground-state properties, particularly on the spin polarization over the whole range of x.