Exchange bias training in La0.7Sr0.3FeO3/Ni79Fe21 films with native surface oxide: First-order reversal curve analysis

Abstract

In conventional magnetometry, exchange bias training (EBT) is mostly evaluated through the major magnetization hysteresis loops (MHLs). We here report a study of EBT by using the first-order reversal curves (FORCs) in the heterostructures of ${\mathrm{SrTiO}}_{3}(001)/{\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{FeO}}_{3}(\mathrm{LSFO})/{\mathrm{Ni}}_{79}{\mathrm{Fe}}_{21}(\mathrm{Py})/{\mathrm{PyO}}_{x}$. It was unraveled that the training effect occurs once after exceeding the left coercivity of the first MHL, while the magnetic coupling from the ultrathin native oxide (${\mathrm{PyO}}_{x}$) mainly contributes to an exchange springlike behavior. Besides for the first MHL, the FORCs corresponding to the second MHL and the quasiequilibrium stage were collected, respectively, which provide a detailed picture of how the magnetization reversal evolves in the training process.