Soft magnetic properties of CoZr thin films for high frequency application

• Main Authors: Meng-hsun Wu, 吳孟勳
• Other Authors: Wen Cheng Chang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/21244983065445363809

碩士 === 國立中正大學 === 物理所 === 98 === The ferromagnetic resonance frequency (f FMR) of the magnetic thin film is proportional to the square root of the saturation magnetization (4πMs) and magnetic anisotropy field (Hk). High 4πMs and high Hk in the film are two crucial points for it to exhibit high f FMR which is promising for making the material for above giga hertz range applications. In this study, the CoZr thin films were prepared by using the oblique deposition method together with an external magnetic field of 1200 Oe. The composition range investigated was typically 5≦x≦17 for Co100-xZrx. It was found that with increasing Zr content, the 4πMs decreases from 12.3 kG for x = 5 to 7.3 kG for x = 17. The Hk of the films increases at first and reaches a peak of 266 Oe for x=9, and hence decreases to 182 Oe for x=17. The Hce (coercivity along the easy axis) of the films decreases at first and reaches a peak of 5.4 Oe for x=14, and hence increases to 6.3 Oe for x=17. The Hch (coercivity along the hard axis) of the films decreases at first and reaches a peak of 1.6 Oe for x=9, and hence increases to 4.4 Oe for x=17. The highest theoretically ferromagnetic resonance frequency of 5 GHz can be achieved when x = 9.In order to reduce the coercivity of the thin film, Cu and Ni20Fe80 were selected to be the underlayer. The results showed that the coercivity can be slightly reduced while the magnetic anisotropy was also slightly decreased. Among them, Co91Zr9(110 nm)/Ni20Fe80(15nm) bilayer exhibits the optimal magnetic properties of 4πMs = 12 kG, Hce = 5.4 Oe, Hch = 0.7 Oe, Hk = 258 Oe and f FMR, cal. = 5 GHz.