We conduct a feasibility study of nitrogen-vacancy (NV) ensemble magnetometry of the two-dimensional ferromagnet Cr2Ge2Te6 (CGT). The studied sample consists of thin flakes of exfoliated CGT...Show moreWe conduct a feasibility study of nitrogen-vacancy (NV) ensemble magnetometry of the two-dimensional ferromagnet Cr2Ge2Te6 (CGT). The studied sample consists of thin flakes of exfoliated CGT stamped onto a diamond with shallow NV centers. First, we simulate the NV center response to the magnetic stray fields produced by a monolayer of CGT and conclude a good signal to noise ratio should be attainable in a shot noise limited picture. Subsequent room temperature photo luminescence experiments reveal two key challenges: optical dimming underneath the samples and inherent low contrast of the NV electron spin resonance (ESR) spectrum. We can explain the optical dimming by a near-surface nanophotonic effect. The low observed contrast can partially be accounted for by the ionization of the shallow NV centers to the neutral charge (NV0). Also, it is found that contrast can be largely regained by rigorous cleaning of the diamond surface.Show less
Spin waves are collective excitations of spins in magnetic materials, that can be used to transport and manipulate spin information in spintronic devices. In this work, we use the magnetic field...Show moreSpin waves are collective excitations of spins in magnetic materials, that can be used to transport and manipulate spin information in spintronic devices. In this work, we use the magnetic field generated by a radio frequency (RF) current in a microstrip to excite surface-confined Damon-Eshbach spin waves in an Yttrium Iron Garnet (YIG) thin film. First, we measure the propagating spin waves by recording the currents they generate via induction in a second microstrip. By sweeping the RF frequency, we map out the spin wave spectrum excited in the YIG. Next, we harness the spin associated to a nitrogen-vacancy lattice defect in diamond (NV center) to locally probe the magnetic stray fields generated by the spin waves. By monitoring the NV center’s electron spin resonance (ESR) contrast and Rabi frequency we register the spectrum of the spin waves in a unique way. Moreover, we directly observe the filter function decay of the spin wave’s magnetic field and characterise resonant spin wave excitation in a microstrip cavity. Finally, we use a single NV center embedded in an AFM scanning probe to directly image the wavefronts of spin waves in YIG. This was never done before and paves the way for magnon imaging at the nanoscale.Show less
