11:45 〜 12:00
▼ [22a-A205-11] Implementation of a highly sensitive magnetic sensor using CoFeB/Y3Fe5O12 bilayer magnonic resonator
キーワード：Spin wave, Magnonic resonator, Magnetic sensor
In this study, we designed a highly sensitive, simple structure and ultra-low power magnetic sensor using a simple CoFeB/Y3Fe5O12(YIG) bilayer structure. We grew a 70-nm-thick YIG thin film using the PLD technique on a Gd3Ga5O12 substrate. A 60 nm thick and 15 mm wide CoFeB stripe was patterned onto the YIG films by photolithography and room-temperature DC magnetron sputtering. Subsequently, a system of two CPWs composed of 90-nm-thick Au was integrated into the YIG film using photolithography and DC magnetron sputtering. We employed a microwave characterization technique using a vector network analyzer connected to two coplanar waveguides labeled CPW1 and CPW2, shown in Figures 1(a) and (b). A DC-biased magnetic field (μ0Hext = 20 mT) was applied where magnetostatic surface SWs were excited. We demonstrated that the CoFeB/YIG bilayer structure could create a sharp rejection band in its spin-wave transmission spectra shown in Figure 1(c). The lowest point of this strong rejection band allows the detection of a slight frequency shift owing to the external magnetic field variation demonstrated in Figures 1(d) and (e). Experimental observations revealed that such a bilayer magnetic sensor exhibits 20 MHz frequency shifts upon an external magnetic field of 0.5 mT. Considering the full-width half maximum of the rejection band, 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 (mT) has been demonstrated using the sharp edge of the rejection band of the CoFeB/YIG bilayer device shown in Figure 1(f). We proposed a Y-shaped SWs interference device with two input arms consisting of CoFeB/YIG and YIG to demonstrate a sensitivity of 10-9 T (nT) at room temperature shown in Figure 1(g).