Progress Towards the Sensing of Short Wavelength Spin Waves In Yttrium Iron Garnet Using Nitrogen Vacancy Spin Qubits

Spin waves are coherent magnetic excitations that can exist in ferromagnets. The state of the art host material for these spin waves is yttrium iron garnet (YIG) due to its low dissipation [1]. Recent experiments have demonstrated the coupling between spin waves in YIG and nitrogen vacancy (NV) spin quibits in diamond, which are well established quantum sensors of magnetic fields. Using NVs, experiments have been able to directly image spin waves in YIG down to around 600 nm [2-3]. Due to the potential of YIG spin waves to be used in magnetic scattering and spintronic applications, it is of interest to image shorter wavelengths of magnons. However, this can be difficult due to the presence of thermal magnetic noise from the YIG, reducing NV coherence properties [4-5]. Here we present techniques to improve the coherence properties of NV centers close to YIG films. These will enhance the sensitivity of future NV/YIG studies opening the possibility to observe short wavelength magnons.



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