Quantum Sensing of Spin Fluctuations of Magnetic Insulator Films with Perpendicular Anisotropy

TL;DR

This paper demonstrates the use of nitrogen vacancy centers in diamond for noninvasive quantum sensing of spin fluctuations in magnetic insulator films, revealing detailed magnetic properties inaccessible to traditional methods.

Contribution

It introduces a novel quantum sensing technique using NV centers to measure intrinsic spin fluctuations in magnetic insulators with perpendicular anisotropy.

Findings

Correlation between NV relaxation rates and magnon density.

Access to magnon band structure via NV-based measurements.

Potential for diagnosing noise in magnetic spintronic devices.

Abstract

Nitrogen vacancy (NV) centers, optically active atomic defects in diamond, have been widely applied to emerging quantum sensing, imaging, and network efforts, showing unprecedented field sensitivity and nanoscale spatial resolution. Many of these advantages derive from their excellent quantum-coherence, controllable entanglement, and high fidelity of operations, enabling opportunities to outperform the classical counterpart. Exploiting this cutting-edge quantum metrology, we report noninvasive measurement of intrinsic spin fluctuations of magnetic insulator thin films with a spontaneous out-of-plane magnetization. The measured field dependence of NV relaxation rates is well correlated to the variation of magnon density and band structure of the magnetic samples, which are challenging to access by the conventional magnetometry methods. Our results highlight the significant opportunities offered by NV centers in diagnosing the noise environment of functional magnetic elements, providing valuable information to design next-generation, high-density, and scalable spintronic devices.