Correlation between local Fe states and magnetoresistivity in granular films containing FeCoZr nanoparticles embedded into oxygen-free dielectric matrix

The paper reports on a comparative study of local Fe states, phase composition and magnetoresistivity of granular nanocomposite films FeCoZr–CaF2 sintered in pure Ar and Ar + O sputtering atmosphere. For the first time peculiarities of temperature and magnetic field dependencies of magnetoresistance are analyzed with respect to partial oxidation of nanoparticles and perpendicular magnetic shape anisotropy.

• Strong relationship between atmosphere of deposition (Ar or Ar+O2), local Fe states, phase composition and magnetoresistance. • Perpendicular shape magnetic anisotropy originating from the formation of columnar agglomerations of nanoparticles. • Tunneling MR in oxidized granular films due to oxide shells formation and suppression of superparamagnetic - ferromagnetic transition.