Novel laser-induced dynamics in exchange-biased systems

¹  School of Physics and Astronomy, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
²  Physics Department, University of California, San Diego - La Jolla, CA 92093-0319, USA

Corresponding author: shimshon@post.tau.ac.il

Received: 26 May 2009
Accepted: 4 September 2009

Abstract

Ultrafast optical excitation of a ferromagnet/antiferromagnet (Ni/FeF₂) exchange bias bilayer produces novel magnetization dynamics unlike ever observed before. An unexpected precession of the magnetization, in reverse magnetic fields that exceed the exchange bias, originates from a reorientation of frustrated spins at the interface. As the laser-excited interface approaches the blocking temperature, an exchange bias reversal can also be induced with a single excitation pulse, showing that not only the ferromagnet but also the antiferromagnet is strongly affected by the optical perturbation. This non-trivial response cannot be extrapolated from the known slow dynamics of magnetic bilayers, and provides important information on the physics of the interlayer coupling.