ULTRAFAST OPTICAL MODULATION OF AN EXCHANGE BIASED FERROMAGNETIC ANTIFERROMAGNETIC BILAYER/

Time-resolved magneto-optical Kerr techniques are employed to study op tically induced ultrafast modulation in an antiferromagnetic (AF) exch ange biased ferromagnetic (FM) thin epitaxial bilayer (NiFe/NiO). The interface region between the antiferromagnetic NiO and coupled ferroma gnetic NiFe layers is photoexcited with femtosecond laser pulses, foll owing which the transient magneto-optical response of the NiFe layer i s measured. When compared with optically induced effects on ''bare'' e pitaxial NiFe thin films, we observe a large enhancement to the transi ent Kerr effect in the exchange biased bilayers, interpreted as a modu lation of the AF/FM exchange coupling on a picosecond timescale. [S016 3-1829(98)51942-X].