磁二向色性光电发射

磁二向色性光电发射（ Ｍ Ｄ Ｐ Ｅ） 技术是结合光电子能谱和磁二向色性技术的磁学测量方法,近年来已成为研究表面、界面和薄膜等低维体系磁性的重要手段。本文概述了其基本原理和实验方法,着重探讨几种 Ｍ Ｄ Ｐ Ｅ 效应的产生及其理论解释,并介绍了 Ｍ Ｄ Ｐ Ｅ 在磁性过渡金属、稀土金属低维体系中的应用。     

光电子衍射与表面结构分析

光电子衍射是近年来发展成熟的研究外延表面和吸附表面的原子位型、结构、化学键、磁性等物理化学性质的表面分析方法。本文概述了其基本原理以及在理论、实践两方面的最新进展。并且具体阐述了在不同的实验条件下光电子衍射基本的数据处理方法 ,并结合一些近几年发展起来的技术如光电子全息、自旋分辨的光电子衍射 (SPPD)、磁二向色性角分布 (MDAD)等讨论了光电子衍射在各种低维体系中的应用     

光电子衍射与表面结构分析

光电子衍射是近年来发展成熟的研究外延表面和吸附表面的原子位型、结构、化学键、磁性等物理化学性质的表达分析方法。本概述了其基本原理以及在理论、实践两方面的最新进展,并且具体阐述了在不同的实验条件下光电子衍射基本的数据处理方法,并结合一些近几年发展起来的技术如光电子全息、自旋分辨的光电子衍射（SPPD）、磁二向色性角分布（MDAD）等讨论了光电子衍射在各种低维体系中的应用。     

半导体超薄层外延技术

分子束外延（ＭＢＥ），金属有机化学气相淀积（ＭＯ－ＣＶＤ），金属有机分子束外延（ＭＯ－ＭＢＥ）以及原子层和分子层外延（ＡＬＥ和ＭＬＥ）等超薄层外延技术，是随着集成电路向高密度集成，高工作速度和超小型化方向发展而形成的一种薄膜制备工艺，并在微电子学、低维物理和材料科学等领域中有着重要的应用．利用这种技术，可以制备各类超高速器件，光电器件及其集成电路．由这种工艺制备的优质超晶格结构为人们更加深入地从理论和实验上揭示二维电子体系的物理性质带来了极大便利，而且一维超晶格的实现也将有赖于超薄层外延生长技术．可以预期，用这种技术还可以制备由半导体、金属以及有机材料相结合的多类型、多组元的多层人工超薄材料。     

甲醛光催化氧化的ESR研究

利用自旋俘获－电子自旋共振方法，使用光催化剂在纯水，甲醛，甲酸水溶液中进行紫外光化学反应。使用自旋捕获剂ＤＭＰＯ俘获反应过程中的自由基中间体。检测到羟基加合物（ＤＭＰＯ－ＯＨ），甲醛基加合物（ＤＭＰＯ－ＣＨＯ），以及碳中心自由基加合物（ＤＭＰＯ－ＣＰ＾－２）的ＥＳＲ信号。这些加合物均产生于溶液的光氧化过程。实验表明，在ＺｎＯ存在的体系中，甲醛易被羟基氧经。水在光氧的过程中起了关键性的作用。     

碳氢碳氟表面活性剂混合胶束的NMR和ESR研究

用ＮＭＲ，ＥＳＲ和表面张力测量研究了３－十二烷氧基－２－羟丙基磺酸钠（ＳＤＥＨＳ）与全氟辛酸钠（ＳＰＦＯ）混合溶液微环境性质，表面张力测定表明长链烷基磺酸盐中嵌入羟丙基后，其表面活性提高，而与ＳＰＦＯ混合溶液的表面活性高于单一的ＳＤＥＨＳ和ＳＰＦＯ，ＮＭＲ和ＥＳＲ研究表明，ＳＤＥＨＳ的碳氢链与ＳＰＦＯ的碳氟链之间有强烈的相互作用，ＳＤＥＨＳ与ＳＰＦＯ形成混合胶束，混合胶束“界面”的微观粘度较ＳＤＥ     

2，2，4－三甲基－1，3－戊二醇脂肪酸双酯中亚甲基质子的磁不等价性

在合成１３种２，２，４－三甲基－１，３－成二醇（ＴＭＰＤ）脂肪酸双酯的基础上，详细讨论了亚甲基中两个磁不等价质子的化学位移，偶合常数，谱线强度和磁不等价性与分子结构的关系。为了使ＴＭＰＤ脂肪酸双脂中各基团的相对取向能满足分子最稳定的条件，提出ＴＭＰＤ脂肪酸酯应按分子构型Ⅱ排列的结论。     

不同注量X射线系统电磁脉冲响应的数值计算

对Ｘ射线在铝制圆柱形模型上产生的系统电磁脉冲现象进行数值计算,采用了二维粒子模拟技术,得到了８个量级范围的Ｘ线入射线入射注量下的ＳＧＥＭＰ计算结果,总结了ＳＧＥＭＰ的场值,分布与Ｘ光注量的变化规律。     

一种新型的基于磁性液体的光纤Sagnac磁场传感器

提出一种使用磁性液体的新型光纤Sagnac磁场传感器.磁性液体具有磁致可变双折射效应和二向色性,在外加磁场作用下,液体中的磁性纳米粒子沿磁场方向结链规则排列,形成各向异性.将其制成液体薄膜,放入具有一段保偏光纤的Sagnac环中,使光纤Saganc干涉仪的正弦形状干涉光谱可随外磁场变化.光纤中传输光垂直经过磁性液体薄膜...     

二安替比林—（邻—乙氧基）苯基甲烷褪色光度法测定微量铜的研究

合成了新试剂二安替比林－（邻－乙氧基）苯基甲烷（ＤＡｏＥＭ），根据Ｃｕ＾２＋对Ｈ３ＰＯ４－Ｍｎ（Ⅱ）－Ｃｒ（Ⅵ）－ＤＡｏＥＭ显色体系的干扰褪色作用，建立了一个测定微量铜的新方法，其检出限为４×１０＾－６ｇ／Ｌ，铜离子含量在２０－１６０μｇ／Ｌ范围内与１ｇ（Ａ０／Ａ）成良好线性关系，体系稳定性和选择性良好，用于铅样中痕量铜的测定，结果满意。     

Prospects and Opportunities of 2D van der Waals Magnetic Systems

The existence of spontaneous magnetization in low dimensional magnetic systems has attracted intensive studies since the early 60s and research remains very active even now. Only recently, magnetic van der Waals (vdW) systems down to a few layers have been broadly discussed for their magnetic order ground states at finite temperature. The naturally inherited layered structure of the vdW magnetic systems possessing onsite magnetic anisotropy from band electrons can suppress the long-range fluctuations. This provides an excellent vehicle to study the transition of magnetism to 2D limits both theoretically and experimentally. Here the current status of 2D vdW magnetic system and its potential applications are briefly summarized and discussed.     

Magnetic 4d systems studied by implanted ions

By application of the perturbed -ray distribution method following heavy-ion reactions and recoil implantation techniques, we have found an experimental way of producing and investigating magnetic 4d states in metals. Strong 4d magnetism has been found for 4d ions in alkali metal hosts and in Pd hosts. In alkali metals, 4d ions reflect the phenomena of well-defined ionic ground states, orbital magnetism, mixed valence, and crystal field splittings smaller than theLS coupling. Magnetic 4d states in alkali metals cannot be described by one-electron approaches based on Anderson-type models, but requires an analysis in terms of many electron ionic configurations exhibiting basic features common to the physics of stable and unstable f stales in metals. In contrast, the local moment formation of 4d and 3d ions in Pd is governed by inter-atomic interactions of the magnetic d states with host d-band electrons, giving rise to spin magnetic behavior of the 4d impurity and to strong spin polarizations of the 4d electrons of the Pd host. Thus, the magnetism and electronic structure of 4d ions in metals exhibit qualitative differences in alkali metal hosts compared to Pd. The existence of magnetic 4d systems strongly depends on the 4d ion species and the host matrix, and on spin fluctuation rates or the corresponding Kondo temperatures. The results can be directly compared to theoretical work and also to the magnetic behavior of 3d ions in sp metal hosts and in hosts with d-band electrons.     

Observation of localized d states in metals

By application of the perturbed γ-ray distribution method combined with heavy-ion reactions and recoil implantation techniques, we have found an experimental was of producing and investigating localized 3d and 4d states in metals. 3d and 4d ions in sp metal hosts, in particular in alkali metals, exhibit the phenomena of large orbital magnetism, extremely small spin fluctuation rates, well defined ionic ground states, mixed valence, and crystal field splittings smaller than theLS coupling. These results upset long standing assumptions about the nature of d states in metals and their magnetic instabilities due to interaction of d orbitals with conduction electrons. If magnetic, the d states of 3d and 4d ions cannot be described by one electron approaches based on Anderson type models but required an analysis based on ionic configurations. The tendencies towards reduced magnetism can be well reproduced by increasing spin fluctuations which gives new insight into antiferromagnetic d-sp exchanges and the Kondo problem for d ions in sp metals. Localized ionic d states, large orbital effects, small crystal fields, and mixed valence-these new phenomena for d ions in sp metals exhibit common basic features with stable and unstable 4f and 5f systems but reflect qualitative differences to the spin dominated magnetism of 3d ions in Cu, Ag, Au and in d metal hosts.     

The Dzyaloshinskii-Moriya interaction in metals

The Dzyaloshinskii-Moriya (DM) interaction in metals is an important mechanism for many magnetic properties. We start with the s-d exchange model and spin-orbit interaction for weak itinerant ferromagnetic systems to establish the form of DM interaction for metallic magnetic systems. The s-d exchange interaction is treated accurately and the conduction electron-mediated magnetism gives a form of DM interaction which is different from that in insulators. The implications of our result to spiral spin states and skyrmion lattices are also discussed.     

Recent progress in the theory of itinerant electron magnetism

A review is given of recent theoretical investigations toward unified understanding of magnetism in narrow-band electron systems. It is emphasized that the classical controversy between the itinerant and localized models have been resolved into a more general and well-defined problem of spin density fluctuations in a general sense. The local moment picture is a limiting form of general spin fluctuations; and in its opposite limit we have weakly ferro- and antiferromagnetic metals. As an approach from the latter limit, the self-consistent renormalization theory of spin fluctuations is shown to have been quite successful in explaining and predicting a number of qualitatively new physical properties of this class of materials. More recent theoretical studies of spin fluctuations from a general point of view interpolating between the above-mentioned two limits seem to lead to a unified picture of magnetism in narrow-band electron systems including 3d transition metals and magnetic compounds.     

The ferromagnetism of ultrathin films; from two to three dimensions

We review the properties of ultrathin ferromagnetic films, with attention to simple physical arguments that outline their principal properties. A ferromagnetic monolayer clearly provides an illustration of two dimensional magnetism. It is argued that the crossover to three dimensional behavior occurs when only a few monolayers are present, both in the low temperature spin wave regime, and near the transition temperature. We discuss anisotropy and its role in inducing long range order in ultrathin films, and spin reorientation transitions.     

Density functional study of LaFeAsO(1-x)F(x): a low carrier density superconductor near itinerant magnetism

Density functional studies of 26 K superconducting LaFeAs(O,F) are reported. We find a low carrier density, high density of states, N(E(F)), and modest phonon frequencies relative to T(c). The high N(E(F)) leads to proximity to itinerant magnetism, with competing ferromagnetic and antiferromagnetic fluctuations and the balance between these controlled by the doping level. Thus LaFeAs(O,F) is in a unique class of high T(c) superconductors: high N(E(F)) ionic metals near magnetism.     

暂态磁性

利用超快脉冲技术研究铁磁金属的暂态磁性与自旋动力学是国际上最近开展起来的磁学研究新领域．文章简单介绍了这一研究领域的基本概念、实验方法和研究进展     

New scientific opportunities for high pressure research by energy-dispersive XMCD

ABSTRACT

XMCD under pressure is used to study the magnetic properties of the transition metal (TM) systems for over 15 years. We present the technique and how it has been developed. The energy dispersive XAS spectrometer is particularly suited for these studies. The effect of pressure on TM magnetism is discussed. Recent studies performed at different edges illustrate the information that can be obtained through XMCD. Finally, some results obtained on TMs are presented, either at the L_II,III edges of 5d metals or at the K edge of 3d metals, which correspond to the energy ranges that can be probed when using diamond anvil cells for high pressure. Different cases are treated: pure 3d metals, alloys, magnetic insulator and inorganic compounds.     

First principle study of the structural,electronic and magnetic properties of Fe,Co, Ni atomic nanochains encapsulated in single walled and double walled beryllium oxygen nanotubes

By using first-principles calculations within the density function theory, the structural, electronic and magnetic properties of transition metals TM (TM=Fe, Co and Ni) atomic chains wrapped in the single walled and double walled BeO nanotubes are investigated. It is found that all these TM chains @ BeONTs systems are ferromagnetic (FM) and a spin splitting between spin up and down is observed. The high magnetic moment and spin polarization of the TM @ BeONTs systems imply that it can be used as magnetic nanostructure and future applications in permanent magnetism, magnetic recording, and spintronics.