Theoretical Calculation of Drag Component of Tensor M in Quantizing Magnetic Field

All the previous homogeneous theories result in M_ΧΧ = 0 which are at variance with the experimental data. It is for this reason, previous theories have consistently used experimental value of M_ΧΧ in calculating thermopower tensor S. The inhomogeneous and non-equilibrium formalism proposed by Dyakin et al. was generalized to including both transverse and longitudinal modes of electron-phonon interaction and considering the broadening of the Landau level. The resulting formula gives theoretical values of M_ΧΧ for GaAs/AlGaAs heterojunctions which are in accord with experimental ,data at oscillation phases but (λ_p/)^l/2 times smaller than experimental data for T = 1.275 K, 2.937 K, 5.005 K and C = 0.20 where λ_p and are the phonon mean free path and effective thickness of the heterojunctions. By means of the semi-empirical formula of MzZ with extra factor (λ_p/)^l/2 in, phonon drag magnetothermopower can be calculated from theoretical values of M_yΧ and M_ΧΧ.     

A Mathematical Representation of Quantizing the Motion of Electrons in a Magnetic Field

It is shown that the concept of a continuous variation in the kinetic energy of a free longitudinal electron motion along the direction of an external magnetic field results in a physically incorrect conclusion on a zero phase volume in the system where the zero Landau lever is realized. Since the kinetic energy of a longitudinal continuous motion is varied in the same way between 0 and 2_B H within each Landau energy level, this problem is circumvented.     

Possibility of Self-Induced Transparency in Multi-Layer Semiconductor Heterostructure Placed in a Quantizing Magnetic Field

The possibility of self-induced transparency is discussed in a semiconductor structure with 3D-quantized electron spectrum. A model structure is proposed, for which a significant decrease of pulse duration and an increase of power is obtained.     

A Mathematical Representation of Quantizing the Motion of Relativistic Electrons in a Magnetic Field

It is shown that the quadratic component of the kinetic energy of continuous longitudinal motion of relativistic electrons in the external magnetic field is varied continuously between 0 and 2(2m _e c ²_B H) within each Landau energy level, undergoing an abrupt change at the boundaries of the levels. This results in the fact that in the quantum limit of a superstrong magnetic field where all electrons are at the zero Landau level, the maximum quadratic component of the kinetic energy of free longitudinal electron motion along the direction of the magnetic field is twice as high as the maximum quadratic component of the kinetic energy of its bound transverse motion.     

Theory of valley-splitting in surface quantum states of Silicon MOSFETS

The experimentally observed removal of valley degeneracy along the (100)-axis in the surface quantum states of Silicon MOSFETS is explained as an effect due to the electric field and spin-orbit interaction. A combination of crystal momentum representation and effective mass theory is used from which results that within the one-band approximation a magnetic field normal to the Si surface and the electric gate field act upon the electrons independently from each other.A short version of this paper was presented at the Frühjahrstagung 1975 der Deutschen Physikalischen Gesellschaft, Verhandl. DPG (VI)10, 412 (1975).     

Dynamics of Electronic States and Magnetoabsorption in 3D Topological Insulators in a Quantizing Magnetic Field

Quantum states have been calculated analytically; the dynamics of a wave packet in a magnetic field has been investigated, and the optical absorption coefficient has been calculated for surface states in 3D topological insulators of the Bi₂Te₃ family. We have detected a qualitative effect of the hexagonal warping of the spectrum on the structure of wavefunctions at the Landau levels, its manifestation in the features of the wave packet dynamics in a quantizing magnetic field, as well as in the frequency dependence of the optical absorption coefficient, in which new peaks that are absent in the isotropic model of the spectrum appear depending on the polarization of the incident wave. The effects considered here can be manifested in the optical and transport experiments with topological insulators, which makes it possible to determine the parameters of their band structure.     

Magnetic Field Effect on Ultrashort Two-dimensional Optical Pulse Propagation in Silicon Nanotubes

Russian Physics Journal - The paper deals with the magnetic field effect which provides a stable propagation of ultrashort pulses in silicon nanotubes from the viewpoint of their waveform. The...     

Effect of Quantizing Magnetic Field on Cyclotron Energy and Cyclotron Effective Mass in Size Quantized Films with Non-Parabolic Energy Band

The Fermi energy, cyclotron energy and cyclotron effective mass of degenerate electron gas in a sizeoquantized semiconductor thin film with non-parabolic energy bands are studied. The influences of quantizing magnetic field on these quantities in two-band approximation of the Kane model are investigated. It is shown that the Fermi energy oscillates in a magnetic field. The period and positions of these oscillations are found as a function of film thickness and concentration of electrons. Cyclotron energy and cyclotron effective mass are investigated as a function of film thickness in detail The results obtained here are compared with experimental data on GaAs quantum wells.     

Effect of Magnetic Field on the Nanohardness of Monocrystalline Silicon and Its Mechanism

The effect of magnetic field on the nanohardness of monocrystalline silicon doped with phosphorous by ion implantation is studied. It is found that a magnetic field of certain parameters can increase the nanohardness of monocrystalline silicon doped with phosphorous by ion implantation, and this increase can be eliminated by annealing monocrystalline silicon doped with phosphorous by ion implantation at 800°C for 780 s. For the monocrystalline silicon doped with phosphorous by ion implantations that have not been exposed to a magnetic field, annealing them at 800°C for 780 s cannot affect their nanohardness, but exposing them to the magnetic field mentioned previously can no longer affect their nanohardness after annealing. The mechanism of all these phenomena is discussed. A possible mechanism that a magnetic field can promote the disbanding of vacancy clusters, and a possible mechanism of magnetically stimulated clusters’ disbanding and magnetoplastic effect are put forward.     

First-Principle Calculation of Thermoelectric Coefficients for the Nanocluster Lattices of Noble Metals

Physics of Atomic Nuclei - The results of calculating the thermal electromotive force for a crystalline state and a model lattice of nanoclusters of noble transition metals Ag, Au, and Pd are...     

Thermoelectric Mechanism of Field Emission from Carbon Nanostructures

Technical Physics - A model describing peculiarities of field emission from carbon nanomaterials is considered. The model is based on inclusion by drag of electrons by ballistic phonons in the...     

Fractional Quantum Hall Effect in SiGe/Si/SiGe Quantum Wells in Weak Quantizing Magnetic Fields

We have experimentally studied the fractional quantum Hall effect in SiGe/Si/SiGe quantum wells in relatively weak magnetic fields, where the Coulomb interaction between electrons exceeds the cyclotron splitting by a factor of a few XX. Minima of the longitudinal resistance have been observed corresponding to the quantum Hall effect of composite fermions with quantum numbers p = 1, 2, 3, and 4. Minima with p = 3 disappear in magnetic fields below 7 T, which may be a consequence of the intersection or even merging of the quantum levels of the composite fermions with different orientations of the pseudo-spin, i.e., those belonging to different valleys. We have also observed minima of the longitudinal resistance at filling factors ν = 4/5 and 4/11, which may be due to the formation of the second generation of the composite fermions.     

Oscillations of Magnetic Fluid Column in Strong Magnetic Field

Russian Physics Journal - The paper considers the results of measuring the elastic parameters (ponderomotive elasticity coefficient, oscillation frequency, attenuation coefficient) of the...     

磁传感器与磁场的测量

在中学物理教学中，研究磁场传统的实验方法是用小磁针显示磁场的方向，用小磁针或铁粉显示磁感线分布．磁针和铁粉用来形象描述磁场功不可没，可对磁感强度的定量研究却显得无能为力．学生也只好在题海中领会感受磁感强度B的大小；1特斯拉有多大?在脑子里只有一个模糊抽象的印象．物理学对电磁现象的研究成果为各行各业提供了先进的检测设备，可是在自身的物理教学中对磁场的实验检测仍停留在4大发明的“司南”时代．近来上海的DIS实验(数字化实验系统)，     

NMR in Magnetic Field of the Earth: Pre-Polarization of Nuclei with Alternating Magnetic Field

The polarization of nuclei in the low static magnetic field \(B_0\) with an alternating magnetic field \(B^{*} (B^{*} \gg B_0)\) at a very low frequency \(f_m\) (but \(f_m\gg 1\) / \({T_1}\) , where \(T_1\) is the spin-lattice relaxation time) has been investigated. The question of the optimization of the energy consumption during the pre-polarization is also considered. The possibilities of the method are illustrated by the observation of nuclear magnetic resonance signals from a few liquids.     

高场水冷磁体上的高精度热电测量装置

拓扑材料是凝聚态物理近些年的一个重要研究领域.在对拓扑材料的研究中,利用较强的磁场可以观测到高度局域电子态中出现的新奇量子态与物理效应.热电效应是指受热材料中的载流子随着温度梯度由高温区往低温区移动时,所产生的电荷堆积的一种现象.热电效应是探究强磁场下拓扑材料反常物性的一种非常有效的手段.然而关于拓扑材料热电效应在强磁场下的研究较少,这主要是因为水冷磁体上缺乏热电效应的相关表征手段.本文针对水冷磁体在工作时机械振动很强且变场速率快的特点,改进了传统的热电测量装置,实现了在水冷磁体中32 T磁场下高精度的热电测量.通过对拓扑材料ZrTe₅和ZrSiSe的热电效应进行测量,验证了该装置的有效性.     

在自由空间里的运动磁场和时变磁场都没有产生电场

在自由空间里,磁场运动时没有产生电场、时变磁场的辐射运动也没有产生电场.故,“磁生电”的真实原因是：金属电子在广义洛伦兹磁力的作用下的流动而形成Ic,却不是法拉第-麦克斯韦-爱因斯坦在自由空间里虚构的位移电流Id.基于唯物主义自然观,联系电磁感应的物质是洛伦兹的金属电子,却不是法拉第-麦克斯韦-爱因斯坦的真空以太.     

Diffusion-Weighted Magnetic Resonance Imaging in an Ultra-Low Magnetic Field

Magnetic resonance imaging is well known as a highly effective technique of medical visualization. One of its relatively new approaches is diffusion imaging. As a rule, the majority of magnetic resonance investigations in biology and medicine tends to be carried out in high magnetic fields (1.5 T and higher), but there are some advantages of the same experiments in low magnetic fields. It can be strongly useful, for example, for designing and testing new pulse sequences, training operators of magnetic resonance imagers, making new phantoms (model objects). In this study, diffusion-weighted imaging experiments in a low magnetic field 7 mT are performed in the first time. Nevertheless, this field is about two orders of magnitude bigger than an extremely low Earth field, and so concomitant gradients and polarization problems do not arise. In particular, diffusion weighted images of combined model samples (phantoms) are presented.     

Viscosity of a Magnetic Fluid in a Strong Magnetic Field

Acoustical Physics - The paper presents an estimate for the viscosity and its increment (“magneto-viscous” effect) in a thin wall layer of a magnetic fluid column oscillating in a tube...