Volume 78, Number 6, June 2007
Article Number 67006
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 05 June 2007
EPL, 78 (2007) 67006
DOI: 10.1209/0295-5075/78/67006

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

M. Hayashi1, 2, L. Thomas1, C. Rettner1, X. Jiang1 and S. S. P. Parkin1

1  IBM Almaden Research Center - 650 Harry Road, San Jose, CA 95120, USA
2  Department of Materials Science & Engineering, Stanford University - Stanford, CA 94305, USA

received 14 January 2007; accepted in final form 3 May 2007; published June 2007
published online 5 June 2007

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 $\sim $1$\hbox{--} $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.

75.75.+a - Magnetic properties of nanostructures.
75.60.Nt - Magnetic annealing and temperature-hysteresis effects.
85.75.-d - Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields.

© Europhysics Letters Association 2007