Modulating The High-frequency Magnetic Characteristics Of FeCo-based Thin Films

With the improvement of information transmission and processing speed, it is required that the magneto electronic devices can work at high frequency band. Soft magnetic materials as the core of these devices require that it must have high resonance frequency and high permeability. In order to achieve this goal, it is necessary to choose the materials with high saturation magnetization, and the high-frequency magnetic properties can be controlled within a wide range. In this thesis, the magnetron sputtering was used to synthesize Fe Co M(M=Zr、Hf、Nb、Nd、B) thin films. The influence of oblique sputtering, using external magnetic field, doping, and using electric field on static magnetism and high frequency characteristics of Fe Co M thin films were studied respectively. The main innovative results are as follows:1. The high-frequency magnetic properties can be controlled within a wide range by using the method of oblique sputtering and the applying bias magnetic fields. As the oblique angle increases, an increase of Hk from 24 Oe to 426 Oe, and increase of resonance frequency fr from 2.0 GHz to 7.5 GHz, and the initial permeability can be controlled from 43 to 737, which also shows good high frequency characteristics.2. The high-frequency magnetism can be greatly optimized by element doping and changing doping concentration. The resonance frequency fr(1.4 ~ 8.5 GHz) and permeability μ(30 ~ 452) can be controlled within a wide range by further changing the oblique angle, and the coercive force can be reduced to 2 Oe which shows excellent soft magnetic properties.3. The strain that induced by the applied DC electric field can further control the size and direction of in-plane uniaxial anisotropy. Not only realize the non-volatile control on the direction of the magnetization, but also can realize the switching between easy and hard axes results from the strain-driven magnetization reorientations by about 90°. As the applied electric fields increase, the magnetic anisotropy is enhanced from 10 Oe to 76 Oe, and increase of resonance frequency fr from 0.7 GHz to 1.8 GHz, while the damping constant decreases sharply.