Ein neues Verfahren zur Berechnung von Einelektronenzuständen in Kristallen

A new method is presented for the calculation of wave-functions and energy-bands of electrons moving in a periodic potential in the one-electron approximation, which is based on different representations of the wave-functions. The wave-functions are expanded in spherical harmonies and radial solutions of the wave equation within a sphere inscribed in the atomic polyhedron. By suitable choice of the radial functions it is possible to obtain wave-functions which are well orthogonal to the functions of the core electrons. Outside the sphere the wave-functions are expanded in plane waves, having the correct translation symmetry. In contrast to other methods using similar expansions, the wave-functions and their first derivatives in our method are continuous in the whole space. These trial functions are introduced into a variational principle equivalent to the Schrödinger equation in which the conditions of continuity of the wave-functions and their first derivatives are taken into account by the method of undetermined multipliers. By an additional variation of the radial functions inside the sphere one may obtain functions which approximate the real functions leaving only an uniform error in all space.     

Thermodynamic behaviour of Rashba quantum dot in the presence of magnetic field

The thermodynamic properties of an In Sb quantum dot have been investigated in the presence of Rashba spin–orbit interaction and a static magnetic field. The energy spectrum and wave-functions for the system are obtained by solving the Schrodinger wave-equation analytically. These energy levels are employed to calculate the specific heat, entropy,magnetization and susceptibility of the quantum dot system using canonical formalism. It is observed that the system is susceptible to maximum heat absorption at a particular value of magnetic field which depends on the Rashba coupling parameter as well as the temperature. The variation of specific heat shows a Schottky-like anomaly in the low temperature limit and rapidly converges to the value of 2kB with the further increase in temperature. The entropy of the quantum dot is found to be inversely proportional to the magnetic field but has a direct variation with temperature. The substantial effect of Rashba spin–orbit interaction on the magnetic properties of quantum dot is observed at low values of magnetic field and temperature.     

介观圆筒持续电流——紧束缚近似下的严格解

证明了含Ａｈａｒｏｎｏｖ－Ｂｏｈｍ型磁通的空心圆筒中环行电流的单电子理论计算公式，它与圆筒形状及载流子属性（电荷与质量）无关，在紧束缚近似下采用完整晶体模型求得能量和电流的严格解，并研究了电流随磁通变化的周期往，以及持续电流的幅值随筒高与筒厚增大的可能性，获得一系列新结果。 关键词：     

里德堡钠原子抗磁谱的模型势计算

用B样条基组展开方法结合模型势计算了里德堡钠原子抗磁谱和相应的振子强度谱.径向和角向均采用高阶B样条基组.计算结果与已有的R-矩阵和多通道量子亏损理论相结合(R-matrix MQDT)法及其他理论计算结果作了比较,几种理论结果在我们所研究的能区内符合得非常好.本文方法较R-ma-trix MQDT法简单,易于推广到交叉电磁场中里德堡原子的精确谱的计算中.     

Spiral magnetic structure in Heisenberg and non-Heisenberg magnets

The possibility of forming a modulated (spiral) magnetic structure in anisotropic Heisenberg and non-Heisenberg magnets with a frustrated Heisenberg exchange interaction has been investigated. It has been demonstrated that, apart from homogeneous (ferromagnetic and quadrupole) states, the Heisenberg magnets with a strong easy-plane anisotropy can have a spiral magnetic structure. The axis of the spiral coincides with the direction of the external magnetic field. The inclusion of the biquadratic exchange interaction leads to a narrowing of the magnetic field region of the existence of the spiral structure. In the absence of the external magnetic field, the spiral structure can be formed only in the case of easy-axis anisotropy.     

Effect of thermal fluctuations on magnetic phase separation and on the parameters of spin-spiral waves

Effects of temperature on magnetic phase separation and on the parameters of spin-spiral waves are studied. The study is performed using the two-dimensional single-band Hubbard model and the Hubbard-Stratonovich transformation. Both commensurate (antiferromagnetic, ferromagnetic) and incommensurate (spiral) magnetic phases are considered. The problem is solved using the static approximation with allowance for transverse fluctuations of the magnetic moment. It is shown that the temperature significantly affects the collinear and spiral magnetic phases. With an increase in the temperature, the phase-separation region near the half-filling is sufficiently reduced and substituted by the antiferromagnetic phase. The results are used for the interpretation of the magnetic properties of cuprates.     

氢原子Rydberg态抗磁谱的高阶B-spline基组计算

在球坐标下采用基组展开方法计算了均匀磁场中的氢原子高Rydberg态能谱和振子强度谱.径向和角向均采用高阶B样条基组. 径向采用B样条基组能很好地描述束缚态与连续态的耦合；角向采用B样条基组有效地减少了基组维数，计算效率得到大幅度提高. 用上述方法计算了磁场中氢原子Rydberg态-40cm^-1到零场电离阈的高精度抗磁谱并与已有理论和实验结果作了比较. 该方法适用于低于离化阈的所有能区的精确谱计算并易于推广到非氢原子、交叉场中的原子以及高于离化阈的正能区光谱的计算. 关键词： 氢原子 B样条基组 能谱 振子强度谱     

Magnetic excitations in multiferroic TbMnO3: evidence for a hybridized soft mode

The magnetic excitations in multiferroic TbMnO3 have been studied by inelastic neutron scattering in the spiral and sinusoidally ordered phases. At the incommensurate magnetic zone center of the spiral phase, we find three low-lying magnons whose character has been fully determined using neutron-polarization analysis. The excitation at the lowest energy is the sliding mode of the spiral, and two modes at 1.1 and 2.5 meV correspond to rotations of the spiral rotation plane. These latter modes are expected to couple to the electric polarization. The 2.5 meV mode is in perfect agreement with recent infrared-spectroscopy data giving strong support to its interpretation as a hybridized phonon-magnon excitation.     

等腰直角三角柱形量子点的能级结构和波函数

采用分离变量法和无限深势阱模型求解了等腰直角三角柱形量子点的能级结构和波函数。给出了能级结构和波函数的表达式，并绘制了前几个本征波函数的等值线。对直角边长5nm，高度5nm的等腰直角三角柱形量子点，其能级的最小值为 。结论可以用于量子计算或量子通信中，如使用一个截面为正方形的柱形结构来存储两个或四个量子信息。也可以用于导波光学中，如用一个正方形的导波结构传输两路或四路光信号。     

Spiral terraces and spin frustration in layered antiferromagnetic Cr(001) films

We have successfully fabricated a novel type of high-density spiral terraces on Cr(001) films. The influence of nanoscale spiral terraces on layered antiferromagnetic ordering of Cr(001) films has been studied at room temperature by direct imaging of both topographic and magnetic structures using spin-polarized scanning tunneling spectroscopy. Spin frustration and asymmetric magnetic ordering due to dense spiral terraces are observed. Sizable modification of the layered antiferromagnetic order is found to be originating from the topological asymmetry as confirmed by the continuum micromagnetic simulation.     

Spiral structures in helicoidal magnets

The structure and properties of two-dimensional spiral textures in helical ferromagnets are studied. The existence of novel types of periodic structures, namely, of spiral lattices, is predicted for these magnetic systems.     

等腰直角三角柱形量子点的能级结构和波函数

采用分离变量法和无限深势阱模型求解了等腰直角三角柱形量子点的能级结构和波函数.给出了能级结构和波函数的表达式,并绘制了前几个本征波函数的等值线.对直角边长5 nm,高度5 nm的等腰直角三角柱形量子点,其能级的最小值为E=0.09209 eV.结论可以用于量子计算或量子通信中,如使用一个截面为正方形的柱形结构来存储两个或四个量子信息.也可以用于导波光学中,如用一个正方形的导波结构传输两路或四路光信号.     

On magnetic transition of the plane spiral in a commensurate intermediate state

The temperature dependence of the wave vector of a plane spiral in rhombohedral crystals is studied. The conditions are shown under which there occurs temperature-induced transition of the spiral structure into intermediate commensurate phase. The instability of paramagnetic phase with respect to the formation of magnetic spiral near a Lifshitz point is investigated.     

Stable spiral domains in ferrite-garnet films

Stable spiral domain structures—spiral domains stabilized by a bubble lattice and lattices of spiral domains—in epitaxial ferrite-garnet films have been experimentally investigated. The thermodynamic approach based on the concept of magnetostatic pressure is applied to explain the behavior of a spiral domain structure with a change in temperature or magnetic field. It is shown that phase transitions in spiral domains are related to phase transitions in the bubble lattice.     

Coupled spin, elastic, and electromagnetic waves in the magnetic of a ferromagnetic spiral phase

The spectrum of coupled spin, elastic, and electromagnetic waves in the magnetic of a ferromagnetic spiral phase is investigated. The frequency dependences of the reflection coefficient of electromagnetic waves from the surface of a semi-infinite magnet for different angles of the spiral are obtained. An acoustic analog of the Faraday effect in the magnetics of a ferromagnetic spiral phase is considered.     

A Bose-Einstein condensate wave-packet as a soliton in an ideal potential well

The normalized soliton wave-functions corresponding to Bose-Einstein condensate (BEC) wave-packets are studied by an analogy to the solutions of the optical cubic Schrödinger equation. In addition, the two fundamental invariants associated with BEC are evaluated.     

Electromagnetic waves reflected from the plate of a magnetic with a ferromagnetic spiral

The spectrum of coupled spin and electromagnetic waves is obtained for a magnetic with a ferromagnetic spiral structure determined by nonuniform exchange and relativistic interactions. It is shown that resonant interaction between spin and electromagnetic waves is possible. The electromagnetic wave reflectance from the plate of a magnetic with a ferromagnetic spiral is calculated for different spiral angles.     

疏松型螺线管电流轴线上磁场的数值计算

应用数值模拟方法，细致地分析了疏松型螺线管电流轴线上的磁场随螺距和轴线上位置的变化关系，计算结果表明，当螺距较大时，其磁场分布与密绕螺线管电流的磁场分布相差很大，磁场沿轴线和垂直于轴线的方向都有分量，螺距越大，垂直于轴线方向的磁场分量越大；但当螺距较小或距螺线管中心较近外，磁场几乎与密切螺线管电流产生的磁场相当，可用表述密绕螺线管电流的轴线上磁场的简单公式来近似。     

Generic spiral spin liquids

Spiral spin liquids are unique classical spin liquids that occur in many frustrated spin systems, but do not comprise a new phase of matter. Owing to extensive classical ground-state degeneracy, the spins in a spiral spin liquid thermally fluctuate cooperatively from a collection of spiral configurations at low temperatures. These spiral propagation wavevectors form a continuous manifold in reciprocal space, i.e., a spiral contour or a spiral surface, that strongly governs the low-temperature thermal fluctuations and magnetic physics. In this paper, the relevant spin models conveying the spiral spin liquid physics are systematically explored and the geometric origin of the spiral manifold is clarified in the model construction. The spiral spin liquids based on the dimension and the codimension of the spiral manifold are further clarified. For each class, the physical properties are studied both generally and for specific examples. The results are relevant to a wide range of frustrated magnets. A survey of materials is given and future experiments are suggested.     

一种螺旋型Blumlein线的阻抗特性分析

提出了一种结构紧凑的长脉冲发生器,该发生器的螺旋型Blumlein线由内导体（含磁体）、螺旋型中筒和外导体（含磁体）构成,该结构实现了螺旋型Blumlein线和Tesla变压器的一体化。通过对螺旋型Blumlein线的波传输过程分析,给出了慢波系数、开关闭合电流、用于描述形成线闭合开关处界面上波行为的变量因子等参数的计算公式。采用PIC软件对螺旋型Blumlein线的部分波传输过程进行数值模拟,慢波系数等参数的模拟值与计算值基本相符。进行了恒阻抗负载下螺旋型Blumlein线的原理性实验,实验得到的负载波形与编程计算得到的波形基本吻合。