Temporal evolution of exchange bias in spin-valve nanowires on the nanosecond time scale

Abstract

Joule heating from current pulses is used to vary the temperature of exchange biased spin-valve nanowires on the nanosecond timescale. By varying the magnitude and duration of a current pulse in the presence of small magnetic fields the temperature dependence of the temporal evolution of the exchange field of the reference magnetic electrode is determined. We observe that with increasing current strength an increasing fraction of the exchange bias anisotropy is reversed consistent with a distribution of exchange bias energies. This reversal takes place on a short time scale of from ∼1-10 nanoseconds, which we attribute to the switching time of the ferromagnetic reference layer. By using sufficiently large current pulses the direction of the exchange anisotropy can be fully and repeatedly reversed on the nanosecond time scale. © Europhysics Letters Association.