YFeCo soft magnetic thin films with high ferromagnetic resonance frequency and low coercivity

High-frequency environments require higher demands on the ferromagnetic resonance frequency (fr) and loss performance of soft magnetic materials applied in electronics. However, it is difficult to simultaneously improve the fr, saturation magnetization (Ms), and loss performance of soft magnetic materials. Based on the FeCo with high Ms and the Y2Co17 with strong in-plane anisotropy, it is a rational route to prepare YFeCo thin films with different compositions, in order to optimize the high-frequency soft magnetic properties. In this study, we prepared YFeCo thin films with compositions of Y2Fe11Co6 and Y2Fe9Co8 via magnetron sputtering. It shows that the YFeCo thin films can exhibit the characteristics of the Y2Co17 phase in addition to the α-FeCo phase. Compared with the FeCo and Y2Co17 thin films, the YFeCo thin films significantly improve fr while maintaining a relatively high Ms. Specifically, the Ms of Y2Fe11Co6 is 15.9 kGs and its fr is 2.95 GHz, while the Ms of Y2Fe9Co8 is 15.4 kGs and its fr reaches even as high as 4.22 GHz. Contributing to the fine grains and uniform dense structure, the YFeCo thin films can maintain a low coercivity. Specifically, the coercivity of Y2Fe9Co8 is 34 Oe, while that of Y2Fe11Co6 is as low as 16 Oe. This study successfully prepared YFeCo thin films with low coercivity and high fr, which is conducive to the application of thin film materials in high-frequency devices.