Coupling of Nitrogen Vacancy Centers to Pinned Domain Walls in Magnetic Nanowires*

Nanodiamonds containing nitrogen vacancy (NV) centers have emerged as a robust system for measuring magnetic structures on the nanoscale. In addition to their use in studying static magnetic structures, such as stationary domain walls^[1], they have recently been used to probe dynamic phenomena, such as ferromagnetic resonance^[2] and spin wave propagation^[3]. Here, we investigate the coupling of NV centers to pinned domain wall oscillations in a notched ferromagnetic nanowire made of permalloy. To design a nanowire that oscillates at NV resonance frequencies, we used micromagnetic simulations to test various wire sizes and notch geometries. Next, we used a pick-and-place method to position the nanodiamonds at the domain wall pinning site using an atomic force microscope. We then performed measurements using microwaves and a homebuilt confocal microscope. These methods pave the way for future measurements of domain wall dynamics with NV centers and more advanced methods of NV qubit control.
[1] Tetienne, J.-P. et al. Nat. Commun. 6, 6733 (2015).
[2] Page, M. R. et al. arXiv:1607.07485 (2016)
[3] Andrich, P. et al. npj Quantum Inf. 3, 28 (2017).