大剂量Mn离子注入GaAs的性质

在室温条件下在半绝缘性GaAs衬底上进行了大剂量Mn离子的低能注入，并进行了不同条件的退火. 借助于X射线衍射(XRD)和高分辨X射线衍射(HR-XRD)进行了结构分析，经过退火后生成的新相衍射峰增多，根据衬底(004)峰摇摆曲线分析结果退火后更多的Mn离子进入晶格. 运用原子力显微镜分析了样品的表面，发现退火后突起的起伏度增加. 磁性分析表明，退火样品的磁化强度增大.     

Magnetic properties of carbon nanosheets

Two-dimensional carbon nanosheets have been fabricated using inductively coupled radio frequency plasma-enhanced chemical vapour deposition. The structural properties of the nanosheets have been characterised using atomic force microscopy, scanning electron microscopy and X-ray diffractometer. The magnetisation of the samples was studied using vibrating sample magnetometer. The magnetisation of the nanosheets was found to be diamagnetic for fast synthesis processes (30 and 60 min). On the other hand, the nanosheets exhibited a weak ferromagnetic response for the slow (120 min) synthesis process. Energy dispersive spectrometry and atomic absorption spectroscopy confirmed that the magnetisation exhibited by the carbon nanosheets was an intrinsic property and that it was not due to contamination from the substrate. Raman spectroscopy studies revealed that the ferromagnetic carbon nanosheets have a higher ratio (1.20) of graphite peak (I _G) to disordered peak (I _D) than normally expected (0.75–0.90). Available data indicated that the magnetisation was due to the presence of structural disorders.     

Detection of NMR signals with a radio-frequency atomic magnetometer

We demonstrate detection of proton NMR signals with a radio-frequency (rf) atomic magnetometer tuned to the NMR frequency of 62 kHz. High-frequency operation of the atomic magnetometer makes it relatively insensitive to ambient magnetic field noise. We obtain magnetic field sensitivity of 7 fT/Hz1/2 using only a thin aluminum shield. We also derive an expression for the fundamental sensitivity limit of a surface inductive pick-up coil as a function of frequency and find that an atomic rf magnetometer is intrinsically more sensitive than a coil of comparable size for frequencies below about 50 MHz.     

自适应卡尔曼滤波在磁干扰姿态测量中的应用

针对姿态测量系统陀螺仪漂移、周围局部磁场干扰制约姿态测量精度的问题,提出一种基于四元数的自适应卡尔曼滤波(q-AKF)的方法。该方法利用陀螺输出建立姿态解算误差角的状态方程,以磁强计输出构造自适应测量噪声协方差矩阵。仿真结果表明,相比无损卡尔曼滤波(UKF)算法和扩展卡尔曼滤波(EKF)算法,采用q-AKF算法补偿得到的姿态角误差不大于0.5°。q-AKF算法对磁强计进行补偿,能够有效抑制陀螺的漂移误差,提高磁干扰环境下姿态解算精度,具有较高的工程应用价值。     

Measurement of 129Xe frequency shift due to Cs–129Xe collisions

Enhancement factor K0, which characterizes NMR and EPR frequency shifts for Cs-129Xe, is measured for the first time. The enhancement factor r-o was measured to be （702±41） at 80 ℃ and （653±20） at 90 ℃, using the NMR frequency shift, detected by atomic magnetometer at a low magnetic field of 100 nT. This result is useful for predicting the EPR frequency shifts for Cs and the NMR frequency shifts for 129Xe in spin-exchange cells.     

微型隧道效应磁强计的设计和加工工艺研究

介绍了一种新型的基于隧道效应的微型磁强计,对其关键工艺进行了分析和实验研究。利用薄片溶解工艺制作了大尺寸的薄膜(3mm×1mm),并且在薄膜的两面都制作了图形结构,拓展了微机械工艺的加工能力     

Magnetic shielding property for cylinder with circular,square, and equilateral triangle holes

The shielding property of cylinder with circular, square, and equilateral triangle holes was investigated by finite element analysis(FEA). The hole area(S_(hole)) plays an important role in magnetic circuit on the surface of cylinder. When Sholeis less than the critical area(S_H), cylinder with three shapes of holes obtained the same remanent magnetization inside,indicating that the shielding property is unaffected by the shape of the hole. Hence, high-permeability material is the major path of the magnetic field. On the condition of S_(hole) S_H, the sequence of the shielding property is equilateral triangle square circular, resulting from magnetoresistance of leakage flux in air dielectric. Besides, the anisotropy of shielding property caused by hole structural differences of the cylinder is evaluated. We find that a good shielding effectiveness is gained in the radial direction, compared with the axis direction. This research focuses on providing a theoretical support for the design of magnetic shield and improvement on the magnetic shielding ability.     

加速度计/磁强计无陀螺捷联惯导姿态解算研究

针对无陀螺捷联惯导系统姿态解算随时间不断积累的问题,提出一种磁强计辅助无陀螺捷联惯导的组合方案,利用磁强计测量的地磁信息来修正无陀螺惯导系统的姿态角误差,提高了姿态角的解算精度。推导了磁强计输出和姿态角之间的关系,在此基础上提出了一种姿态优化算法,介绍了算法的基本原理;建立了误差四元数的姿态组合模型,并采用反馈校正完成动态条件下姿态的确定;最后对姿态误差角进行了仿真研究,仿真结果表明该方法有效地抑制了误差的发散。     

Organometallic L-Alanine Cadmium Iodide Crystals for Optical Device Fabrication

Single crystals of L-alanine cadmium iodide (LACI) were grown by the slow evaporation technique at room temperature. A single-crystal X-ray diffraction (SXRD) model was used to evaluate the crystal structure of the as-grown LACI crystal. The energy dispersive X-ray (EDX) analysis and ultraviolet-visible-near infrared (UV-vis-NIR) transmittance studies were carried out, and the results reveal the presence of elements in the title compound. From the transmittance data, the optical bandgap as a function of photon energy was estimated, and the different optical constants were calculated. A fluorescence study was performed for the LACI crystal. Thermogravimetric and differential thermal analyses have also been studied to investigate the thermal property of the LACI crystal. The efficiency of the second harmonic generation (SHG) of the title crystal was investigated. The magnetic and electrical properties were estimated by the vibrating sample magnetometer (VSM) analysis and impedance study, respectively.     

Cs原子磁力仪共振谱线宽度的研究

介绍了Cs原子无自旋交换弛豫磁力仪(Cs-SERFM)的工作原理;分析了Cs泡温度105℃条件下,缓冲气体He的压强对Cs原子横向弛豫及线宽的影响,给出了惰性气体He的最佳压强为350×133.3 Pa;讨论了共振谱线的宽度与温度之间的关系,在105℃时Cs-SERFM谱线宽度仅为3.7 Hz。