Bi底层对FePt薄膜的影响

利用磁控溅射的方法，在玻璃基片上制备了以Bi为底层的FePt薄膜，经不同温度真空热处理得到L1₀-FePt薄膜.研究了Bi做底层对FePt薄膜的有序化温度及矫顽力H_c的影响.实验结果表明：以Bi做底层的FePt薄膜在350℃实现低温有序，同时其H_c也有大幅度提高，并且可以在更大成分范围内获得H_c较高的L1₀-FePt薄膜.利用X射线光电子能谱研究了薄膜中Bi原子的分布情况，利用X射线衍射研究了薄膜的晶体学结构变化.结果表明,Bi底层在退火过程中的扩散促进了FePt薄膜有序度的升高. 关键词： 0-FePt薄膜')" href="#">L1₀-FePt薄膜 有序化温度 底层 扩散     

Amorphous Ni-Al underlayer-accelerated L10 ordering transition of FePt thin films

In the present study, we succeeded in accelerating the L1₀ ordering transition of FePt thin films by employing amorphous Ni-Al as underlayers. The coercivity H_c = 5 kOe and ordering parameter S = 0.67 of FePt thin films deposited on a Ni-Al underlayer with a thickness of ∼5 nm after 380 °C annealing for 30 min are significantly higher than those H_c = 0.4 kOe and S = 0.35 of the films without the Ni-Al underlayer. The L1₀ ordering process of and the coercivity of FePt thin films can be significantly tuned by varying the thickness of the Ni-Al underlayer.     

Effect of Cr100−xTix (x = 0-19 at.%) alloy underlayers on the high coercivity of FePt thin film below the substrate temperature of 250 °C

The effect of Cr_100−xTi_x underlayer on orderd-L1₀ FePt films was investigated. A low-temperature ordering of FePt films could be attained through changing the Ti content of Cr_100−xTi_x underlayer. The ordering temperature of the 30 nm FePt film grown on 20 nm Cr₉₀Ti₁₀ underlayer was reduced to 250 °C which is practical manufacture process temperature. An in-plane coercivity was very high to 6000 Oe and a ratio of remnant magnetization (M_r) to saturation magnetization (M_s) was as large as 0.85. This result indicates that the coercivity obtained at 250 °C by the effect of CrTi underlayer is significantly higher than those obtained at 250-275 °C by the effect of underlayers in other conventional studies. The prominent improvement of the magnetic properties of ordered FePt thin films at low temperature of 250 °C could be understood with considering the strain-induced ordering phase transformation associated with lattice mismatch between Cr underlayer and FePt magnetic layer due to an addition of Ti content.     

缓冲层Ta对FePt薄膜L10有序相转变及矫顽力的影响

制备了Ta/FePt/C系列多层膜，研究了样品在不同温度退火后的磁特性和微结构.实验结果表明，不同厚度的Ta缓冲层具有不同的微结构特征，显著影响FePt层的L1₀有序相的形成及相应的矫顽力.当Ta缓冲层较薄，Ta层为非晶态，且较为粗糙，由此使FePt在界面处产生较多的缺陷并导致较高密度的晶界，在退火过程中，受束缚相对较弱的非晶态的Ta原子比较容易沿FePt的缺陷和晶界处向FePt层扩散，使FePt在相变过程中产生的应力比较容易释放，同时，Ta在扩散过程中产生的缺陷，降低了FePt有序 关键词： FePt薄膜 0相')" href="#">L1₀相 原子扩散     

室温生长MgO底层诱导(001)取向FePt薄膜的有序化过程对FePt成分的依赖

室温下通过磁控溅射在表面热氧化的Si基片上生长了MgO/Fe_xPt_100-x双层膜和Fe_xPt_100-x单层膜系列样品，Fe_xPt_100-x的原子成分x=48—68.研究了热处理前后不同成分FePt薄膜的晶体结构和磁性的变化，尤其是MgO底层的引入对FePt的晶体结构和磁性的影响 关键词： FePt(001)薄膜 0相')" href="#">L1₀相     

The effect of thickness and annealing condition on the microstructure and magnetic properties of Fe/Pt multilayer thin films

[Fe(0.5 nm)/Pt(0.5 nm)]₄₀, [Fe(1 nm)/Pt(1.5 nm)]₂₀ and [Fe(3 nm)/Pt(3 nm)]₁₀ multilayer were prepared by DC magnetron sputtering. By conventional furnace annealing (CA) at 270–600 °C for various time, all of the films still remained the disordered structure with the soft magnetic phase. By rapid thermal annealing (RTA) at 500 °C for various time, we obtained the [Fe(1 nm)/Pt(1.5 nm)]₂₀ and [Fe(3 nm)/Pt(3 nm)]₁₀ films with L1₂ ordered FePt₃ phase which was almost ferromagnetic at room temperature. However, the [Fe(0.5 nm)/Pt(0.5 nm)]₄₀ films was still disordered state even under RTA. Compared with CA, RTA exposed an outstanding effect on accelerating the phase transition when the film thickness is over [Fe(0.5 nm)/Pt(0.5 nm)]₄₀.     

Magnetization reversal of ultrathin Fe film grown on Si（111） using iron silicide template

Ultrathin Fe films were epitaxially grown on Si（lll） by using an ultrathin iron silicide film with p（2 × 2） surface reconstruction as a template. The surface structure and magnetic properties were investigated in situ by low energy electron diffraction （LEED）, scanning tunnelling microscopy （STM）, and surface magneto-optical effect （SMOKE）. Polar SMOKE hysteresis loops demonstrate that the Fe ultrathin films with thickness t 〈 6 ML （monolayers） exhibit perpen-dicular magnetic anisotropy. The characters of M-H loops with the external magnetic field at difference angles and the angular dependence of coercivity suggest that the domain-wall pinning plays a dominant role in the magnetization reversal process.[第一段]     

The effect of deposition temperature on the intermixing and microstructure of Fe/Ni thin film

The physical vapour deposition of Ni atoms on α-Fe(001) surface under different deposition temperatures were simulated by molecular dynamics to study the intermixing and microstructure of the interfacial region. The results indicate that Ni atoms hardly penetrate into Fe substrate while Fe atoms easily diffuse into Ni deposition layers. The thickness of the intermixing region is temperature-dependent, with high temperatures yielding larger thicknesses. The deposited layers are mainly composed of amorphous phase due to the abnormal deposition behaviour of Ni and Fe. In the deposited Ni-rich phase, the relatively stable metallic compound B₂ structured FeNi is found under high deposition temperature conditions.