Resonant activation of a synthetic antiferromagnet.

ABSTRACT

The magnetic decay time of a synthetic antiferromagnet comprised of two closely spaced magnetic dipoles is measured in the presence of microwave excitation. The system is known to be highly stable with respect to switching between its two antiparallel ground states under quasistatic magnetic fields. We show that an order of magnitude lower field can switch the pair, provided the field is applied in resonance with the optical eigenmode of the collective spin dynamics in the system. We furthermore show that thermal agitation can play an essential role in spin-flop switching for resonant excitations of near- or subcritical amplitude.