Ultrafast manipulation of antiferromagnetism of NiO

Photoexcitation of antiferromagnetic NiO leads to ultrafast reorientation of Ni2+ spins due to change of the magnetic anisotropy. Recovery of the magnetic ground state occurs as coherent oscillation of the antiferromagnetic order parameter between hard- and easy-axis states manifesting itself as quantum beating. The coherence time is similar to1 ns with the beating frequency being determined by the anisotropy energy.