Effects of annealing on properties of spin-valve pinned with FeMn alloy

The magnetic properties of spin-valve pinned by FeMn layer were investigated after it was annealed at different temperatures. Its property was dependent on the vacuum annealing temperature. The pinning field could be increased through annealing at a temporature lower than 200degreesC;the pinning field would reduce and other properties be deteriorated as the annealing temperature was higher than 200degreesC; the pinning effect lost and giantmagnetic resistance disappeared at 300degreesC. Based on the results of AES analysis it was concluded that the diffusion in spin-valve multilayer was along grain boundary.

Magnetic property and interlayer segregation in spin valve metal multilayers

The experimental results show that the exchange coupling field of NiFe/FeMn for Ta/ NiFe/FeMn/Ta multilayers is higher than that for the spin valve multilayers Ta/NiFe/Cu/NiFe/FeMn/ Ta. In order to find out the reason, the composition and chemical states at the surfaces of Ta(12nm)/ NiFe(7nm), Ta(12nm)/NiFe(7nm)/Cu(4nm) and Ta(12nm)/NiFe(7nm)/Cu(3nm)/NiFe(5nm) were studied using the X-ray photoelectron spectroscopy (XPS). The results show that no elements from lower layers float out or segregate to the surface for the first and second samples. However, Cu atoms segregate to the surface of Ta(12nm)/NiFe(7nm)/Cu(3nm)/NiFe(5nm) multilayers, i.e. Cu atoms segregate to the NiFe/FeMn interface for Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers. We believe that the presence of Cu atoms at the interface of NiFe/FeMn is one of the important factors causing the exchange coupling field of Ta/NiFe/FeMn/Ta multilayers to be higher than that of Ta/NiFe/Cu/NiFe/ FeMn/Ta multilayers.

Interlayer segregation of Cu atoms in Ta/NiFe/Cu/NiFe/FeMn/Ta spin-valve multilayers and its influence on magnetic properties

Experimental results show that the exchange coupling field (H-ex) of NiFe/FeMn for Ta/NiFe/FeMn/Ta multilayers is higher than that for spin-valve multilayers Ta/NiFe/Cu/NiFe/FeMn/Ta. In order to find out the reason, the composition and chemical states at the surface of Ta(12 nm)/NiFe(7 nm), Ta(12 nm)/NiFe(7 nm)/Cu(4 nm), and Ta(12 nm)/NiFe(7 nm)/Cu(3 nm)/NiFe(5 nm) were studied using x-ray photoelectron spectroscopy. The results show that no elements from lower layers float out or segregate to the surface in the first and second samples. However, Cu atoms segregate to the surface of Ta(12 nm)/NiFe(7 nm)/Cu(3 nm)/NiFe(5 nm) multilayers, i.e., Cu atoms segregate to the NiFe/FeMn interface for Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers. We believe that the presence of Cu atoms at the interface of NiFe/FeMn is one of the important factors which causes the exchange coupling field (H-ex) of Ta/NiFe/Cu/NiFe/FeMn/Ta to be weaker than that of Ta/NiFe/FeMn/Ta. (C) 2002 American Institute of Physics.

Species；valve size；and pretreatment effects on delta O-18 and delta C-13 values of ostracod valves from Lake Qinghai；Qinghai-Tibet Plateau

IEECAS SKLLQG

Redescription of Camallanus hypophthalmichthys Dogel and Akhmerov, 1959 (Nematoda : Camallanidae) and its first record from fishes in China

The nematode Camallanus hypophthalmichthys Dogel and Akhmerov, 1959 is redescribed from specimens collected from the intestine of the bighead carp Aristichthys nobilis, from Liangzihu Lake (Yangtze River basin), Hubei Province, central China. The light and scanning electron microscopical examination made it possible to study in detail the morphology of this so far little-known species and to confirm its validity. The main specific features of C. hypophthalmichthys distinguishing it from the most similar Camallanus spp. is the presence of 3 small caudal processes on the male tail tip, 13-16 longitudinal ridges on the inner surface of the valve of the buccal capsule, and the arrangement of preanal and postanal genital papillae in the male. This finding represents a new host record, the first record of this parasite in the Yangtze River basin, and the first documented record of C. hypophthalmichthys from China. Camallanus hypophthalmichthys is considered a specific intestinal parasite of fishes of the cyprinid Hypophthalmichthyinae.

Interlayer segregation in magnetic multilayers and its influence on exchange coupling

Experimental results show that the exchange coupling field (H-ex) of NiFe/FeMn for Ta/NiFe/FeMn/Ta multilayers is higher than that for spin-valve multilayers Ta/NiFe/Cu/NiFe/FeMn/Ta. X-ray photoelectron spectroscopy shows that Cu atoms segregate to the NiFe/FeMn interface for Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers. While studying Ta/X(X=Bi,Pb,Ag,In)/NiFe/FeMn multilayers, we also find that X atoms segregate to the NiFe/FeMn interface, which results in a decrease of the H-ex. However, a small amount of Bi, Pb, etc. deposited between Cu and pinned NiFe layer for Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers can increase H-ex. (C) 2003 American Institute of Physics.

Interlayer segregation of Cu atoms in metal multilayers

The experimental results show that the exchange coupling field H.. of NiFe/FeMn for TalNiFe/FeMn/Ta multilayers is higher than that for the spin valve multilayers Ta/NiFe/Cu/NiFe/FeMn/Ta. The composition and chemical states at the surface of Ta(12nm)/NiFe(7nm), Th(12nm)/NiFe(7nm)/Cu(4nm) and Ta(12nm)/NiFe(7nm)/Cu(3 nm)/NiFe(5 mn) were studied by using x-ray photoelectron spectroscopy. The results show that no element from the underlayers Boats out or segregates to the surface for Th(12 nm)/NiFe(7nm), Ta(12 nm)/NiFe(7nm)/Cu(4 mn). However, Cu atoms segregate to the surface of Ta(12 nm)/NiFe(7nm)/Cu(3nm)/NiFe(5nm) multilayers, i.e. to the NiFe/FeMn interface for Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers. We believe that the presence of Cu atoms at the interface of NiFe/FeMn is one of the important factors which will cause the exchange coupling field H.. of Ta/NiFe/FeMn/Ta multilayers to be higher than that of Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers.

MBE Growth of High Electron Mobility InP Epilayers

The molecular beam epitaxial growth of high quality epilayers on （100） InP substrate using a valve phosphorous cracker cell over a wide range of P/In BEP ratio （2.0-7.0） and growth rate （0.437 and 0. 791μm/h）. Experimental results show that electrical properties exhibit a pronounced dependence on growth parameters,which are growth rate, P/In BEP ratio, cracker zone temperature, and growth temperature. The parameters have been optimized carefully via the results of Hall measurements. For a typical sample, 77K electron mobility of 4.57 × 10^4 cm^2/（V · s） and electron concentration of 1.55×10^15 cm^-3 have been achieved with an epilayer thickness of 2.35μm at a growth temperature of 370℃ by using a cracking zone temperature of 850℃.

ECR离子源高真空微调针阀控制系统

本论文首先介绍ECR（电子回旋共振）离子源的基本原理及其发展，在此基础上讲述了近物所的14.5GHzECR离子源的结构和特点。本论文主要内容是介绍所研制的适用于30KV高压端的ECR离子源高真空微调针阀控制系统。此系统被控对象是位于ECR源上的高真空微调针阀，它与地面之间有20～30KV的电位差。论文中首先阐述此控制系统研究的背景，并对ECR离子源电气参数控制的特点进行了说明。根据被控对象的情况以及对系统提出的指标，详细讲述了此控制系统的软、硬件实现。硬件包括步进电机、步进电机驱动器、轴编码器等。软件包括译码编程。然后从总体介绍此控制系统的功能结构，再分步讲述发射器、接受器、译码等各功能模块的实现过程。此控制系统的最大特点是使用光路实现高压绝缘，这为解决位于ECR离子源高压端器件的控制问题提出新思路。本系统的光路采用红外线发射接收系统，以空气为传输介质，依据光信号的有无接收控制信息，此方式效果好、易于实现。在系统中，使用光路传输装置定位，聚集透镜聚集，增加信号强度，提高抗干拢能力。而且此光路传输系统价格便宜，易于实现，可靠性好。在整个控制系统方案调研期间，对各种控制方式进行了比较和实验，在此基础上，确定了一个比较经济实用和具有高可靠性的方案。经过设计电路原理图、绘制印制线路板、加工印制线路板、购买元器件、组装电路后，首先成功地进行了离线调试，最后，将整个系统模拟实际环境进行调试实验。整个系统实现了稳定可靠的工作，达到了预期的设计指标，精度好于要求的千分之一。由于时间紧张和条件的限制，该系统还未在现场设备上进行实验。因此，在今后的工作中，此控制系统还需要在条件具备时，在现场设备上进行实验和考验。此外，为满足国家大科学工程兰洲重离子冷却储存环的要求，我参与了在14.5GHz ECR离子源上进行afterglow工作模式的实验，首次产生了高电荷态脉冲束流Ar~(11+)和Ar~(12+)。论文最后一部分给出了初步实验结果，并对结果进行了分析和解释。

On-line introduction of high-pressure gas-liquid sample for capillary gas chromatographic analysis

An on-line sample introduction technique in capillary gas chromatograph (CGC) for the analysis of high-pressure gas-liquid mixtures has been designed and evaluated. A sample loop of 0.05 muL and a washing solvent loop of 0.5 muL are mounted on a 10-port switching valve, which serves as the injection valve. A capillary resistor was connected to the vent of sample loop in order to maintain the pressure of the sample. Both the sample and the washing solvent are transferred into the split-injection port through a narrow bore fused silica capillary inserted into the injection liner through a septum. The volume of the liner is used both as the pressure-release damper and evaporation chamber of the sample. On-line analysis of both reactants and resultants in ethylene olimer reaction mixture at 5 MPa was carried out, which demonstrated the applicability of the technique. (C) 2004 Elsevier B.V. All rights reserved.

Study of an electroosmotic pump for liquid delivery and its application in capillary column liquid chromatography

A packed-bed electroosmotic pump (EOP) was constructed and evaluated. The EOP consisted of three capillary columns packed in parallel, a gas-releasing device, Pt electrodes and a high-voltage power supply. The EOP could generate output pressure above 5.0 MPa and constant flow rate in the range of nl/min to a few mul/min for pure water, pure methanol, 2 mM potassium dihydrogenphosphate buffer, the buffer-methanol mixture and the pure water-methanol mixture at applied potentials less than 20 W The composition of solvent before/after pumping was quantitatively determined by using a gas chromatograph equipped with both flame ionization detector and thermal conductivity detector. It was found that there were no apparent changes in composition and relative concentrations after pumping process for a methanol-ethanol-acetonitrile mixture and a methanol-water mixture. Theoretical aspect of the EOP was discussed in detail. An capillary HPLC system consisting of the EOP, an injection valve, a 15 cm x 320 mum i.d., 5 mum Spherigel C(18) stainless steel analytical column, and an on-column UV detector was connected to evaluate the performance of the EOP. A comparative study was also carried out with a mechanical capillary HPLC pump on the same system. The results demonstrated that the reproducibility of flow rate and the pulsation-free flow property of the EOP are superior to that of mechanical pump in capillary HPLC application. (C) 2004 Elsevier B.V. All rights reserved.