Picosecond creation of switchable optomagnets with giant photoinduced Kerr rotations in polar antiferromagnetic (FeZn)MoO
arXiv:2109.03498 · doi:10.1103/PhysRevX.9.031038
Abstract
On-demand spin orientation with long polarized lifetime and easily detectable signal is an ultimate goal for spintronics. However, there still exists a trade-off between controllability and stability of spin polarization, awaiting a significant breakthrough. Here, we demonstrate switchable optomagnet effects in (FeZn)MoO, from which we can obtain tunable magnetization, spanning from -40 to 40 of a saturated magnetization that is created from zero magnetization in the antiferromagnetic state without magnetic fields. It is accomplishable via utilizing circularly-polarized laser pulses to excite spin-flip transitions in polar antiferromagnets that have no spin canting, traditionally hard to control without very strong magnetic fields. The spin controllability in (FeZn)MoO originates from its polar structure that breaks the crystal inversion symmetry, allowing distinct on-site - transitions for selective spin flip. By chemical doping, we exploit the phase competition between antiferromagnetic and ferrimagnetic states to enhance and stabilize the optomagnet effects, which result in long-lived photoinduced Kerr rotations. The present study, creating switchable giant optomagnet effects in polar antiferromagnets, sketches a new blueprint for the function of antiferromagnetic spintronics.