Local Ferromagnetic Resonance Measurements of Mesoscopically Patterned Ferromagnets Using Deterministically Placed Nanodiamonds

Off-resonant detection of domain wall oscillations using deterministically placed nanodiamonds

“…Device 1 is a 300 nm wide nanowire with a 120 nm wide defect (a notch); device 2 is a 350 nm wide nanowire with a 140 nm wide defect. We use a pick-and-place protocol reported earlier 4 and in Methods to position a nanodiamond directly above the respective defect in each device (Fig. 3).…”

“…We use standard electron beam lithography, electron beam thin film deposition, and a liftoff process to prepare 10 nm thick Py semicircular nanowires with a notch-shaped defect in the center. 100 nm diameter nanodiamonds (Adámas Nanotechnologies, 3 ppm NV) are placed using an AFM pick-and-place technique outlined elsewhere 4 , yielding results like those shown in Fig. 3a, c.…”

“…GHz-scale ferromagnetic dynamics, such as spin waves, vortex gyrations, and domain wall oscillations, offer both a fascinating target for quantum sensing and a potential qubit-driving source in quantum computing applications. One of these qubits, the nitrogen-vacancy (NV) center in diamond, has been previously used to detect ferromagnetic resonance [1][2][3][4] , spin-wave scattering 5 , spin-wave frequency multiplication 6 , and vortex gyrations 7 . Ferromagnetic dynamics have also been explored as potential sources of microwave driving for NV centers: NV-magnon coupling was first reported in 2017 8 , then electrically tuned in subsequent works 9,10 , and vortices have been shown to enhance NV spin rotation during qubit addressability experiments 11 .…”

“…The detection is carried out using spin relaxometry measurements (pulsed optically detected magnetic resonance) of NV centers located in a nanodiamond that is deterministically positioned near the DW (Fig. 1) via a pick-and-place protocol reported recently 4 . Our platform uses NiFe (Permalloy, Py) patterned into a semicircular nanowire with a centrally positioned notch; this allows us to probe a pinned single DW which is nucleated at the notch by applying a radially directed external magnetic field.…”

Sensing spin wave excitations by spin defects in few-layer-thick hexagonal boron nitride

“…Over the past decade, nitrogen-vacancy (NV) centers, one of the most prominent candidates of this class of defects, have been applied as effective sensors of local spin transport and dynamic behaviors in various condensed matter systems ( 8 ). Notable examples include off-resonant NV detection of magnon excitations by nanodiamonds ( 9 – 11 ), nanoscale measurements of spin chemical potential in a magnetic insulator ( 12 ), probing spin torque driven auto-oscillations ( 13 , 14 ), magnetic resonance imaging of spin-wave propagation ( 15 , 16 ), and others ( 8 , 17 ). More recently, emergent color centers hosted in layered van der Waals (vdW) crystals such as transition metal dichalcogenides and hexagonal boron nitride (hBN) became new contenders in this field ( 18 , 19 ).…”