Sensitivity and Noise of a Magnetic Field Sensor Based on Magnetostatic Spin Wave YIG Device and Its Integrated Electronics

Since few decades, research in the magnonic area, which studies the phenomenon of spin waves propagation in magnetic materials, has grown simultaneously with the emergence of the so-called spintronic and nano-structured magnetic materials. Recent works exposed the interest of such devices for designing magnetic field sensors, considering the dependence of the transmission parameter S
₂₁
regarding the external applied magnetic field, for excitation frequency of several GHz. In this paper, we have investigated the ability of spin wave propagation phenomenon to be used as a magnetometer by characterizing its expected performances, particularly the output sensitivity, expressed in unit of V/T. The sensing element is designed from a YIG film (10 mm x 5 mm x 19.4 μm) deposited on GGG substrate. It is placed on a microstrip antenna transducer made of two copper lines, respectivelyto excite and measure the spin waves. The excitation is provided by a sine electromagnetic wave at a fixed frequency f
₀
= 1.146GHz. The induced spin waves propagate along the main length direction of the YIG material and induce a voltage signal at the output antenna at the carrier frequency f
₀
. When the external DC magnetic field varies, it yields a modulated signal. The dedicated and reduced electronic conditioning circuitry, based on a I/Q quadrature demodulator, allows to extract the field variations information with an output sensitivity of about 20V/T. Considering that the dominating noise sources are those due to the electronic conditioning circuitry, a sensor equivalent magnetic noise √ level of several nT/ Hz in white noise region was obtained.