Off-resonant imaging of magnon propagation using NV quantum sensors

Magnons or spin waves are magnetic excitations that can propagate over long distances and have been used as signal carriers in electronics, due to their low energy dissipation

and the ability to manipulate upcoming magnetic memories directly [1]. Quantum sensors - especially nitrogen vacancy (NV) centers in diamond - have been successfully

employed to sense and image magnons, enabling detailed studies of magnons and their coupling to other materials [2] [3]. Usually however a magnetic bias field needs to be

tuned to bring the magnons in resonance with the NV center spin transition. This is not always desirable, as an applied bias field changes the behavior of the magnons as

well as that of potential interaction targets. Here we present a protocol that allows for off-resonant sensing of magnons with NVs based on the AC-stark effect. We demonstrate

that we can use NVs to image magnon propagation at magnetic bias fields not constrained to resonance conditions.

[1] Y. Wang et al, Science, 366(6469):1125–1128 (2019). doi: 10.1126/science.aav8076

[2] T. X. Zhou et al, Proc. Natl. Acad. Sci. U.S.A., 118(25) (2021). doi:10.1073/pnas.2019473118

[3] I. Bertelli et al, Adv Quantum Tech, 4(12) (2021). doi: 10.1002/qute.202100094