Development of a Magnonic-Based Magnetic Sensor: Comparison of Two Different Implementations With YIG Material

In a ferromagnetic material exposed to a strong magnetic field, the spin wave describes the propagation of the phase shift of precessing spins at the same frequency over the time. In recent years, this subject has been of a great interest in the field of instrumentation and data transmission. Although several studies have shown a strong potential of magnonics for the design of a magnetic field sensor, few studies have been interested in the realization of such sensors and are limited to the measurement of scattering parameters. Here, we describe the development of a magnetic field sensor, using the variations in the propagation of the spin wave induced by the external magnetic field variation. We detailed the full implementation of the system, based on magnonics devices along with its associated electronic. The proposed implementation is mainly based on a quadrature I/Q demodulation to produce an output signal whose variations reflect the variations of the external applied magnetic field. The sensing element is designed from a yttrium iron garnet (YIG) film deposited on the gadolinium gallium garnet (GGG) substrate. It is placed on an optimized microstrip antenna transducer made of two copper lines, respectively, to excite and measure the spin waves. With the help of characterization measurements (S-parameters) carried out with a VNA, field sensitivities, expressed in V/T, could be estimated from S-parameters. Two kinds of magnonic devices have been implemented: one using spin-wave reflections at each YIG edge and other one using spacial filtering by YIG material microstructuring. Their performances regarding the magnetic sensitivity are compared. Finally, this first implementation of such a sensor, based on YIG magnonic material, exhibits a magnetic noise level of about 100 pT/ $\surd $ Hz at 1 kHz and a usable bandpass of 100 kHz. This is quite promising for a new sensor technology, leaving room for further developments.