Off-Resonant Detection of Domain Wall Oscillations Using Deterministically Placed Nanodiamonds

TL;DR

This paper demonstrates off-resonant detection of GHz-scale domain wall oscillations using deterministically placed nanodiamonds with NV centers, revealing sensitive measurement of magnetic dynamics and implications for quantum spintronics.

Contribution

It introduces a novel off-resonant detection technique for domain wall oscillations using NV centers in nanodiamonds, highlighting sensitivity to patterning imperfections and potential for quantum device applications.

Findings

Detected GHz-scale DW oscillations off-resonantly.

Observed discrepancies indicating sensitivity to patterning imperfections.

Suggested pathways for quantum spintronic device development.

Abstract

Nitrogen-vacancy (NV) centers in diamond offer a sensitive method of measuring the spatially localized dynamics of magnetization and associated spin textures in ferromagnetic materials. We use NV centers in a deterministically positioned nanodiamond to demonstrate off-resonant detection of GHz-scale microwave field driven oscillations of a single domain wall (DW). The technique exploits the enhanced relaxation of NV center spins due to the broadband stray fields generated by an oscillating DW pinned at an engineered defect in a lithographically patterned ferromagnetic nanowire. Discrepancies between the observed DW oscillation frequency and predictions from micromagnetic simulations suggest extreme sensitivity of DW dynamics to patterning imperfections such as edge roughness. These experiments and simulations identify potential pathways toward quantum spintronic devices that exploit current driven DWs as nanoscale microwave generators for qubit control, greatly increasing the driving field at an NV center and thus drastically reducing the {\pi} pulse time.