Sign Reversal and Tunability of Exchange Bias in Nanoscale AuFe Alloy Film: A New Material for Spintronic Application

We report here sign reversal and tunability of exchange bias in AuFe cosputtered films of thickness about 63 nm. As deposited film exhibits exchange bias effect at room temperature without external triggering field and its magnitude increases gradually with decrease in temperature down to 5 K. Upon irradiation with 100 MeV Au9+ ions at a fluence of 5*1013 ions/cm2, hysteresis loop shifts completely from origin towards positive field side at room temperature and reverses sign when temperature is reduced to 5 K as studied by SQUID magnetometry. A well defined uniaxial magnetic anisotropy has been seen by magneto optical Kerr effect (MOKE) in as deposited film as well as in irradiated one. The results are explained on the basis of stress induced magnetic anisotropy in thin films.