Single-Shot Laser-Induced Switching of an Exchange Biased Antiferromagnet

Ultrafast manipulation of magnetic order has challenged the understanding of the fundamental and dynamic properties of magnetic materials. So far single-shot magnetic switching has been limited to ferrimagnetic alloys, multilayers, and designed ferromagnetic (FM) heterostructures. In FM/antiferromagnetic (AFM) bilayers, exchange bias (He) arises from the interfacial exchange coupling between the two layers and reflects the microscopic orientation of the antiferromagnet. Here the possibility of single-shot switching of the antiferromagnet (change of the sign and amplitude of He) with a single femtosecond laser pulse in IrMn/CoGd bilayers is demonstrated. The manipulation is demonstrated in a wide range of fluences for different layer thicknesses and compositions. Atomistic simulations predict ultrafast switching and recovery of the AFM magnetization on a timescale of 2 ps. The results provide the fastest and the most energy-efficient method to set the exchange bias and pave the way to potential applications for ultrafast spintronic devices. Antiferromagnets are an exciting class of materials due to their inherently THz dynamics and complex interactions. Here, the highlight of the work is the demonstration that it is possible to switch the coupled antiferromagnet with a single femtosecond laser pulse. The results provide a means of direct and deterministic control of an antiferromagnet on the sub-picosecond timescale. image