{Cu3}单分子磁体在磁场中的热纠缠

本文研究单分子磁体Na₉[Cu₃Na₃(H₂O)₉ (α-AsW₉O₃₃)₂]·26H₂O中三角自旋 环在磁场作用下的热纠缠性质, 利用数值计算求出任意两个Cu²⁺离子量子比特之间的配对纠缠度, 分别记为C₁₂, C₂₃和C₁₃. 研究结果表明, 磁场的方向和大小以及温度对配对纠缠度具有重要影响, 而且参数的变化对C₁₂, C₂₃和C₁₃的影响也是各不相同. 给出外加三个不同方向的磁场时, 配对纠缠度C₁₂, C₂₃和C₁₃各自对应的临界温度T_c随磁场强度的变化图, 由此可以得到单分子磁体三角自旋环中存在纠缠态的参数范围. 通过选择适当的磁场方向和大小以及温度等实验参数, 可以有效地调节和提高单分子磁体中的配对纠缠度. 关键词： 配对纠缠 单分子磁体 三角自旋环     

纳米晶永磁Pr2Fe14B微磁学有限元法的模拟计算研究

根据实验数据，构造了接近实际纳米晶永磁Pr2Fe14B的样品，用微磁学有限元法进行了模拟计算.计算结果表明，晶界处各向异性的下降会导致矫顽力减小、剩磁值增大，而晶界处交换作用常数的减小则会使剩磁值减小、矫顽力增大.通过对实验样品的模拟研究发现，晶界处各向异性和交换作用常数的共同减小能够同时拟合出真实的矫顽力和剩磁值.模拟计算与实验在退磁曲线形状上的差距则说明模拟还存在不足. 关键词： 纳米晶永磁 磁滞回线 矫顽力 剩磁     

磁性材料进展

本文介绍了磁性材料近年来的进展及应用，主要是在高技术领域的发展和在提高性能、扩大应用范围中有那些技术加工手段及其所起的作用。     

六层加侧混合型摇摆器磁场的理论计算与数值模拟

 利用文献[1，2]给出的结果，提供了六层加侧混合型摇摆器中永磁体磁场的计算公式和软铁磁场计算的积分方程式。对周期长度lw =1.6cm，磁极间隙g=0.5cm的情况，计算了单向聚焦和双向聚焦两种不同构形的磁场分布，并得到了g /lw =1/3条件下，峰值磁场Bw超过1特斯拉的设计指标。     

实验和数值模拟超导绕组的机械特性

为了减少环氧浸渍的超导磁体的锻炼和退化效应，基于实验和数值模拟研究了在热应力的电磁力的条件下超导绕组的机械特性；研究的基本目的是决定超导复合线圈基本的材料特性，其中复合超导绕组的杨氏模量和热收缩系数是基本的参数，使用这些参数我们可以用有限元方法精确地研究超导磁体的机械特性，通过分析各种超导磁体的设计，判断好的和坏的磁体设计，从而发展新的超导磁体的设计标准，形成超导磁体的设计和建造的基本方法，本中我们将通过实验和FEA模拟研究复合绕组的基本参数和应用特性。     

Structure comparison between Th2Zn17-type and TbCu7-type Sm–Fe intermetallic compounds and their nitrides by means of 57Fe-Mössbauer spectroscopy

Samarium–iron intermetallic compounds were prepared by a melt spinning method with low and high wheel speeds, which resulted in a Th₂Zn₁₇-type and a TbCu₇-type structure, respectively. Structure comparison between these types was investigated for Sm–Fe intermetallic compounds and their nitrides by ⁵⁷Fe-Mössbauer spectroscopy.     

ECR离子源六极永磁体的设计研究

分别从材料、结构、尺寸等方面全面地研究了Halbach结构六极永磁铁的设计方法.针对个别磁块可能存在的退磁问题给出了相应的解决方案.通过优化结构,使六极磁铁在离子源等离子体弧腔内壁产生的磁场达到最大.用POISSON,PERMAG,TOSCA等多个磁场模拟程序计算模拟了六极磁场的大小与分布,并给出了一些相应的曲线     

Deterministic Generation of Quantum State Transfer Between Spatially Separated Single Molecule Magnets

We propose a new scheme for realizing deterministic quantum state transfer （QST） between two spatially separated single molecule magnets （SMMs） with the framework of cavity quantum eleetrodynamics （QED）. In the present scheme, two SMMs are trapped in two spatially separated optical cavities coupled by an optical fiber. Through strictly numerically simulating, we demonstrate that our scheme is robust with respect to the SMMs＇ spontaneous decay and fiber loss under the conditions of dispersive SMMs-field interaction and strong coupling of cavity fiber. In addition, we also discuss the influence of photon leakage out of cavities and show that our proposal is good enough to demonstrate the generation of QST with high fidelity utilizing the current experimental technology. The present investigation provides research opportunities for realizing QST between solid-state qubits and may result in a substantial impact on the progress of solid-state-based quantum communications network.     

An optimized magnet for magnetic refrigeration

A magnet designed for use in a magnetic refrigeration device is presented. The magnet is designed by applying two general schemes for improving a magnet design to a concentric Halbach cylinder magnet design and dimensioning and segmenting this design in an optimum way followed by the construction of the actual magnet. The final design generates a peak value of 1.24 T, an average flux density of 0.9 T in a volume of 2 L using only 7.3 L of magnet, and has an average low flux density of 0.08 T also in a 2 L volume. The working point of all the permanent magnet blocks in the design is very close to the maximum energy density. The final design is characterized in terms of a performance parameter, and it is shown that it is one of the best performing magnet designs published for magnetic refrigeration.     

永磁体外部磁场的不均匀性研究

从永磁体的分子电流观点、退磁场、工艺等出发, 以矩形永磁体为例, 从理论上分析了影响永磁体外部磁场不均匀性的各种因素.研究结果表明, 永磁体外部磁场宏观不均匀性(好场区均匀度和面积相对大小) 和空间距离及永磁体的外形设计密切相关. 退磁场对永磁体外部磁场微观不均匀性有着复杂影响. 永磁体工艺如粉末颗粒、取向度、烧结凝固、机械加工等将影响永磁体外部磁场的不均匀性, 如磁化偏角、对称性、光滑性等. 关键词： 永磁体 外部磁场 不均匀性 退磁场