Optical Detection of Magnetoelastic Dynamics in an Antiferromagnetic Insulator

Antiferromagnets are promising for spintronic applications due to their high resonant frequencies and small or vanishing net magnetization. To fully realize the advantageous properties of antiferromagnets, control and read-out of the Neel vector orientation is crucial. Accordingly there is much interest in reliable Neel vector switching. The often large magnetoelastic coupling in antiferromagnets can be used to manipulate the Neel vector in insulating materials. Here we present a scheme for exciting antiferromagnetic dynamics in NiO and α-Fe₂O₃ using surface acoustic waves generated electrically by an interdigitated transducer on the piezoelectric substrate PMN-PT. By modulating the strain-induced magnetic anisotropy below the antiferromagnetic resonance frequency, we expect to generate dynamics that reduce the switching threshold. The resulting dynamics are detectable using paramagnetic nitrogen-vacancy centers in diamond, which enable noninvasive optical detection of magnetic field fluctuations produced by spin dynamics. Insight into the nature of magnetoelastically-generated dynamics is fundamental for engineering devices capable of robust control of the Neel vector.