Microstructure Characteristics And Magnetic Anisotropy Of Epitaxial Co-W Perpendicular Thin Films

Nowadays, the magnetic recording is one of the most important ways to store information. As the development of computer and internet technology, the data storage with higher density is urgently required. The perpendicular magnetic recording is one way to realize the ultra-high-density storage. Co-W is one of potential candidates for next-generation high density magnetic recording due to their high magnetic anisotropy energy.In this thesis, a series of Co-W alloy films with different contents and thicknesses were prepared by DC magnetron sputtering. Microstructures, crystalline orientation and magnetic properties of Co-W thin films were systematically investigated by Vibrating sample magnetometer (VSM) and X-Ray diffraction (XRD). And the correlations between crystalline structures and magnetic properties were clarified. And the main impact factors of magnetic anisotropy were revealed. The main conclusions are as follows:The epitaxial growth of hcp Co-W films with hcp Ru seed layers are well oriented controlled. And the epitaxial growth relationships between substrates and thin films are MgO(111)//Ru(00·2)//Co-W(00·2). The high quality of thin films is confirmed by Φ-scan and omega scan.Along with the increase of the magnetic layer thin-film thicknesses, the intensity of Co Co(00·2) diffraction peak is gradual enhanced, and the position of diffraction peaks has a little left misregistration. As the increase of the W contents, the diffraction angle direction of Co(00·2) peak is significantly reduced.The atomic stacking faults which produced in epitaxial films are mainly growth faults, and this kind of stacking fault is extending up from the single crystal substrate. The density of growth faults is less than10%, the values of density of growth faults and fcc/hcp volume ratio are essentially unchanged, independent of W ceontents and thicknesses.The saturation magnetization Ms increases as the thickness and the W content decreases. While the W content is up to14at.%, the Ms is reduced to500emu/cc.The lattice constants a and c of the Co-W films increase with increasing thicknesses and W content. The increase in Ku is coincident with a reduction of the c/a ratio. The results show that the effect of stacking faults and fcc/hcp volume ratio on magnetic anisotropy of Co-W thin films is little. The Ku is mostly related to the hcp Co-W lattice c/a ratio.The bulk anisotropy Kv and surface anisotropy Ks are changed by the change in thicknesses and compositions, which has a certain impact on the magnetic anisotropy constant, leading to the relationship between Ku and1/t is non-monotonic linear.