  Deterministic all-optical control of magnetization without an applied
magnetic field has been reported for different materials such as ferrimagnetic
and ferromagnetic thin films and granular recording media. These findings have
challenged the understanding of all-optical helicity-dependent switching of
magnetization and opened many potential applications for future magnetic
information, memory and storage technologies. Here we demonstrate optical
control of an antiferromagnetic layer through the exchange bias interaction
using the helicity of a femtosecond pulsed laser on IrMn/[Co/Pt]xN
antiferromagnetic/ ferromagnetic heterostructures. We show controlled switching
of the sign of the exchange bias field without any applied field, only by
changing the helicity of the light, and quantify the influence of the laser
fluence and the number of light pulses on the exchange bias control. We also
present the combined effect of laser pulses and applied magnetic field. This
study opens applications in spintronic devices where the exchange bias
phenomenon is routinely used to fix the magnetization orientation of a magnetic
layer in one direction.
