Role of interparticle coupling on the tunneling magnetoresistance of granular films in interacting superparamagnetic system

A phenomenological model is employed to explain the departure of H/T scaling of tunneling magnetoresistance (TMR) in Co 0.43 (ZrO 2 ) 0.57 granular films (see [B.J. Hattink, M. Garcia del Muro, Z. Konstantinovic, X. Batlle, A. Labarta, Phys. Rev. B 73 (2006) 045418]). The model bases on the modification of Langevin function by taking into account the field-dependent correlation length, in the framework of Inoue–Maekawa model. Both TMR –H and TMR –H/T curves can be reproduced very well by this model, indicating that the interparticle coupling plays an important role on TMR in the interacting superparamagnetic systems. The influence of anisotropy and spin polarization of the magnetic particles on TMR –H/T curves is also discussed.