Sensitivity enhancement in magnetic sensor using CoFeB/Y3Fe5O12 resonator

Magnonics, an emerging research field that uses the quanta of spin waves as data carriers, has a potential to dominate the post-CMOS era owing to its intrinsic property of ultra-low power operation. Spin waves can be manipulated by a wide range of parameters; thus, they are suitable for sensing applications in a wide range of physical fields. In this study, we designed a highly sensitive, simple structure, and ultra-low power magnetic sensor using a simple CoFeB/Y3Fe5O12 bilayer structure. We demonstrated that the CoFeB/Y3Fe5O12 bilayer structure can create a sharp rejection band in its spin-wave transmission spectra. The lowest point of this strong rejection band allows the detection of a small frequency shift owing to the external magnetic field variation. Experimental observations revealed that such a bilayer magnetic sensor exhibits 20 MHz frequency shifts upon the application of an external magnetic field of 0.5 mT. Considering the lowest full width half maximum, which is about 2 MHz, a sensitivity of 10(-2) mT order can be experimentally achieved. Furthermore, the higher sensitivity in the order of 10-6 T (mu T) has been demonstrated using the sharp edge of the rejection band of the CoFeB/Y3Fe5O12 bilayer device. A Y-shaped spin waves interference device with two input arms consisting of CoFeB/Y3Fe5O12 and -Y3Fe5O12 has been theoretically investigated. We proposed that such a structure can demonstrate a magnetic sensitivity in the range of 10(-9) T (nT) at room temperature. The sensitivity of the sensor can be further enhanced by tuning the width of the CoFeB metal stripe.

Automated summary

Magnonics, an emerging research field that uses spin waves as data carriers, has the potential to dominate the post-CMOS era with its ultra-low power operation. In this study, a highly sensitive and low power magnetic sensor was designed using a simple CoFeB/Y3Fe5O12 bilayer structure. Experimental observations demonstrated a frequency shift of 20 MHz upon the application of an external magnetic field of 0.5 mT, indicating a sensitivity of 10(-2) mT order. The sensitivity can be further enhanced by tuning the width of the CoFeB metal stripe.