Features of Magnetoresistance of Straintronics Element in the Presence of Bistable Magnetic States

The paper presents the findings of a study investigating the dependence of the magnetoresistance of a magnetic straintronics element comprising a multilayer film nanostructure of Ta (5 nm)/FeNiCo (20 nm)/CoFe (10 nm)/Ta (5 nm) layers, successively sputtered on a silicon substrate, on the strength of the external remagnetization magnetic field and compression stress. It has been established that the experimental value of the maximum change in the magnetoresistance of the nano-structure at remagnetization of layers is less than the theoretical value. This discrepancy can be attributed to the random character of the orientational phase transition of the bistable magnetic system in proximity of the critical value of the external magnetic field. A variational method of theoretical approximation of magnetoresistance dependences has been developed, which enables determining unknown parameters of magnetic nanolayers from experimental data, for example, the H_an anisotropy field and H_σ magnetostriction field. The developed theory is shown to be in quantitative agreement with experimental results.