Giant planar Hall effect in reactive sputtered epitaxial CrxFe3–xO4 films

Abstract

The epitaxial CrxFe3-xO4 films were fabricated by dc reactive sputtering on MgO (001) substrates. The longitudinal resistivity ρxx was enhanced 3 orders of magnitude with the increase of Cr content x from 0 to 0.87. The tunneling magnetoresistance like planar Hall effect in the CrxFe3-xO4 films was observed while the angle between ⟨100⟩ in (001) oriented films and the direction of magnetic field is 45° and 135°, respectively. Both the phase relation of angular dependent planar Hall resistivity ρxy and the numeral relation of ρxy with longitudinal resistivity difference ρ//−ρ⊥ cannot be understood by the planar Hall effect expression in isotropic magnetic medium. The largest planar Hall resistivity was ∼105 μΩ cm for x = 0.71, which is one, two, and six orders of magnitude larger than that in Fe3O4, GaMnAs, and ferromagnetic metals, respectively. The giant planar Hall resistivity ρxy is weak saturated at high fields and increases with the magnetic field. This giant planar Hall effect in the highly resistive CrxFe3-xO4 films is closely correlated to the longitudinal resistivity and antiphase boundaries.