Concentration and heat treatment effects on magnetoresistive properties of Ag-added Ni80Fe20 film systems

Abstract

• The film phased state does not depend on the Ag concentration. • Different types of magnetoresistive effect was observed. • The maximum value of isotropic MR observed at the addition of Ag with c = 60 at.%. • Temperature dependences of LMR and TMR in the range from 300 to 900 K are presented. Comprehensive investigation of the phase state and the magnetoresistive properties of Ag-added Ni 80 Fe 20 film systems with a total thickness of 55 nm in a wide range of component concentration under the heat treatment within the temperature range 300–900 K was presented. Thin films based on permalloy Ni 80 Fe 20 with addition of Ag atoms were prepared by the electron-beam co-evaporation method at room temperature. Their composition and phase state were studied using X-ray spectrometry and electron diffraction methods. The film phased state remained unchanged when adding Ag within the entire range of investigated compositions. The process of the high-temperature treatment also did not affect their structure. Different types of magnetoresistive effect were observed. The anisotropic magnetoresistive effect appeared in systems with low concentration of Ag atoms. With increasing concentration of the non-magnetic atoms the shape of magnetoresistive field dependences transformed to the linear-like drop curves without hysteresis that led to the appearance of the isotropic magnetoresistive effect in the film plane. The maximum isotropic magnetoresistance was observed at the Ag concentration of about 60 at.%. The magnitude of this maximum value increased after annealing at 500 K and significantly reduced after high-temperature annealing at 900 K.