Development of High-Sensitivity Fluxgate Magnetometer Using Single-Crystal Yttrium-Iron Garnet Thick Film as the Core Material
Abstract:
Traditionally, a fluxgate sensor is made of amorphous metallic magnetic ribbons by which the second-order harmonics is characterized in relation to an imposed dc field. Resolution of the sensor device is limited by Barkhausen jumps generated in the core region. In contrast to the conventional approach we propose to perform fluxgate operation coherently involving detection of the generated harmonics of all orders, or to apply the matched filter theory invoking autocorrelation of the signal-waveform itself. As such, noise influence is minimized, since noise can only add to the detection scheme incoherently at each individual harmonic frequencies. In order to achieve this goal we choose to work with insulator cores, such as single-crystal yttrium-iron-garnet YIG thick films. Due to the nearly perfect crystalline structure of YIG films we expect magnetization processes taking place on the film plane arise, instead of domain-wall motion, mainly from magnetization-vector rotation, since nucleation of reversal domains are energetically not favorable. As such, Barkhausen noise is reduced, resulting in a high sensitivity of the fluxgate device. Our long-term goals are to fabricate efficient fluxgate sensors using YIG films as the core material providing the following advantages reliability, ruggedness, and economy. Most importantly, the improved detection scheme allows the fluxgate magnetometer to be applied to dynamic signals, not necessarily to be restricted to the traditional usage detecting static or quasi-static magnetic signals. For example, we anticipate sensitive magnetic recording heads will be made of fluxgate sensors in the future to characterize digital signals flowing at high repetition rates.