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本文采用扩展Hubbard模型, 加上长程关联哈密顿量,在自然边界条件下用自洽场方法研究了有限长反式聚乙炔链中极化子的问题。计算了长程电子关联对极化子的影响并计算了极化子的长程关联能。计算发现长程电子关联使极化子的位形变宽变浅(局域性减弱),在极化子区域,长程电子关联能比平均长程电子关联能要大。当链长增加到100格点以上时,电子极化子和空穴极化子的平均关联能趋于-0.1663eV,而在极化子区域,电子极化子和空穴极化子的平均关联能趋于-0.1868eV。 相似文献
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研究了电子的自旋相关的隧穿和极化。在外加磁场的作用下,自旋向上的电子与自旋向下的电子具有不同的隧穿系数。当电子的自旋方向与磁场方向相反时,其隧穿概率受到磁场的抑制而变小;反之,当两平行时,电子的了隧穿系数增大。这种差异可以用本中定义的自旋极化率来表示。本对不同磁场下的自旋极化率进行了计算,结果也表明当电子的动能较小,这种自旋极化的效应越显。 相似文献
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慢电子与He和Ne原子弹性碰撞的极化作用及散射截面计算 总被引:1,自引:1,他引:0
李萍 《原子与分子物理学报》1993,10(4):2967-2971
本文对慢电子与原子碰撞的一种常用的极化势模型进行了修正,使其在近区描述的入射电子使靶原子的极化作用更符合实际。用此修正后的极化势,在0.2-30eV能量范围内,本文还计算了电子被He和Ne原子弹性散射的总截面和微分散射截面。结果有很大改进,与实验符合得较好,说明本文的极化势修正是合理的。 相似文献
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本文采用扩展Hubbard模型,加上长程关联哈密顿量,在自然边界条件下用自洽场方法研究了有限长反式聚乙炔链中极化子的问题.计算了长程电子关联对极化子的影响并计算了极化子的长程关联能.计算发现长程电子关联使极化子的位形变宽变浅(局域性减弱),在极化子区域,长程电子关联能比平均长程电子关联能要大.当链长增加到100格点以上时,电子极化子和空穴极化子的平均关联能趋于-0.1663eV,而在极化子区域,电子极化子和空穴极化子的平均关联能趋于-0.1868 eV. 相似文献
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简单介绍了极化电子束的获得,即极化电子源,讨论了对电子束极化度的测量,极化电子与原子散射,以及极化电子束在固物理、生物物理、核物理与粒子物理中的应用. The getting of polarized electrons was briefly introduced, that is the source of polarized electrons. The measurement of polarization in future, the application of polarized electrons in atomic and molecular physics, condensed physics, biological physics, nuclear and particle physics were discussed. 相似文献
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讨论了液晶相位可变延迟器(liquid crystal variable retarder, LCVR)在自旋极化电子产生方面的应用.LCVR控制入射光子的偏振度,从而实现对自旋极化电子束极化方向的调制.采用LCVR代替1/4波片和Pockels盒的优点在于其对入射光方向不敏感,传输直径大,不需要机械转动即可大波长范围的延迟,且易于校准.另外,还研制了旋转检偏器,通过示波器读出,对光子偏振性进行检测并对LCVR进行校准.
关键词:
自旋极化电子源
液晶相位可变延迟器
极化方向 相似文献
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采用扩展的SSH模型,加上电子相互作用和长程电子关联,用自洽迭代的方法研究了聚噻吩链中的极化子问题,计算了电子相互作用和长程电子关联对极化子位形和电荷密度的影响,获得了长程电子关联使极化子位形变小,极化子区域变窄,电荷密度震荡减弱,对聚合物中电子的输运的影响不能忽略的有益结果. 相似文献
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Direct observation of spin dependent electronic structure of GaAs using spin polarized photoemission
The spectrum of spin plarization P(hv) of electrons photoemitted from negative electron affinity GaAs using circularly polarized light, 1.5 eV < hv < 3.6 eV, was measured by Mott scattering; it exhibits structure derived from the spin orbit split energy bands near Γ and L. 相似文献
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H. Boersch J. Lemmerich R. Schliepe 《Zeitschrift für Physik A Hadrons and Nuclei》1964,182(2):166-170
The valence electrons in sodium vapour were aligned by optical pumping to a polarization between 5% and 15%. An electron beam of 10?12 A current, 10?2rad divergency and 1 mm diameter has been obtained by ionisation of the sodium vapour with uv-light. This electron beam was polarized up to 2% as measured by Mott scattering. 相似文献
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Y. Totsuka H. Baba J. A. Behr T. Iguri M. Ikeda T. Kato H. Kawamura R. Kishi C. D. P. Levy Y. Nakaya K. Ninomiya H. Nishio J. Onishi R. Openshaw M. Pearson E. Seitaibashi S. Tanaka R. Tanuma T. Toyoda K. Watanabe J. Murata 《Physics of Particles and Nuclei》2014,45(1):244-248
The MTV experiment (Mott Polarimetry for T-Violation Experiment) is running from 2009 at TRIUMF, which aims to search a large non-standard T-Violation in polarized nuclear beta decay. Existence of transverse polarization of electrons emitted from polarized 8Li nuclei, which are produced at TRIUMF-ISAC and stopped inside an aluminum stopper, is investigated. We utilize a Mott polarimeter consists of a planer drift chamber, measuring backward scattering left-right asymmetry from a thin lead analyzer foil. In this paper, preliminary results from the first physics run performed in 2010 are described. 相似文献
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Relativistic electron scattering from freely movable proton/μ~+ in the presence of strong laser field
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《中国物理 B》2019,(9)
We have investigated the electron scattering from the freely movable spin-1/2 particle in the presence of a linearly polarized laser field in the first Born approximation.The laser-dressed state of electrons is described by a time-dependent wave function which is derived from a perturbation treatment.With the aids of numerical simulations, we explore the dependencies of the differential cross section on the laser field intensity as well as the electron-impact energy.Due to the mobility of the target, the differential cross section of this process is smaller than that of Mott scattering. 相似文献
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An analysis of Luttinger's theorem shows that – contrary to recent
claims – it is not valid for a generic Mott insulator. For a
two-orbital Hubbard model with two electrons per site the crossover
from a non-magnetic correlated insulating phase (Mott or Kondo
insulator) to a band insulator is investigated. Mott insulating
phases are characterized by poles of the self-energy and
corresponding zeros in the Greens functions defining a “Luttinger
surface” which is absent for band insulators. Nevertheless, the
ground states of such insulators with two electrons per unit cell
are adiabatically connected. 相似文献
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A. P. Potylitsyn 《The European Physical Journal C - Particles and Fields》2010,70(1-2):107-111
The asymmetry of bremsstrahlung by transversely polarized electrons using Sommerfeld–Maue wave functions has been calculated. In order to simplify the final formula the relativistic approximation has been used. The results obtained show a linear dependence of the asymmetry on the atomic number Z for the range 4≤Z≤26. It is shown that the approach developed gives the zeroth asymmetry for ultrarelativistic energies as expected but for initial electron energies ~5 MeV the asymmetry may achieve a magnitude ~8% (for Z=26). Polarimetry of electrons with energy higher than 1 MeV (where conventional Mott polarimeters have large experimental difficulties) may be carried out using the bremsstrahlung process providing a reasonable asymmetry and high cross section. 相似文献
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New trial wave functions, constructed explicitly from the unique Mott insulating state with antiferromagnetic order, are proposed to describe the ground state of a Mott insulator slightly doped with holes or electrons. A rigid band is observed as charged quasiparticles with well-defined momenta being realized in these states. These states have much less superconducting correlations than previously studied ones. Small Fermi patches obtained are consistent with recent experiments on high T(c) cuprates doped lightly with holes or electrons. 相似文献
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It has been experimentally found that, under the static compression of a calcium crystal at room temperature, it undergoes a series of structural phase transitions: face-centered cubic lattice → body-centered cubic lattice → simple cubic lattice. It has been decided to investigate precisely the simple cubic lattice (because it is an alternative lattice) with the aim of elucidating the possibility of the existence of other (nonstructural) phase transitions in it by using for this purpose the Hubbard model for electrons with half-filled ns-bands and preliminarily transforming the initial electronic system into an electron–hole system by means of the known Shiba operators (applicable only to alternative lattices). This transformation leads to the fact that, in the new system of fermions, instead of the former repulsion, there is an attraction between electrons and holes. Elementary excitations of this new system are bound boson pairs—excitons. This system of fermions has been quantitatively analyzed by jointly using the equation-of-motion method and the direct algebraic method. The numerical integration of the analytically exact transcendental equations derived from the first principles for alternative (one-, two-, and three-dimensional) lattices has demonstrated that, in systems of two-species (electrons + hole) fermions, temperature-induced metal–insulator phase transitions of the Mott type are actually possible. Moreover, all these crystals are in fact excitonic insulators. This conclusion is in complete agreement with the analytically exact calculations of the ground state of a one-dimensional crystal (with half-filled bands), which were performed by Lieb and Wu with the aim to find out the Mott insulator–metal transition of another type. 相似文献
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Pavlov VV Pisarev RV Gridnev VN Zhukov EA Yakovlev DR Bayer M 《Physical review letters》2007,98(4):047403
We demonstrate that optical pumping by circularly polarized light at the charge-transfer transition can induce spin and orbital polarizations in the strongly correlated Mott insulators R(2)CuO(4) (R=Pr, Nd, Sm) providing a means of ultrafast nonlinear manipulation of spin states on time scales of less than 150 fs. We propose a model which includes both orbital- and spin-related processes possessing different spectral and temporal properties. This allows us to model the optical response of antiferromagnetic Mott insulators to circularly polarized light and estimate the spin relaxation time as tau(s) approximately 30-50 fs. 相似文献
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We propose to use the exciton coupling between electrons and holes in different quantum wells to reach a strong Coulomb drag effect. The drag has to be really strong below the Mott transition when the most of the carriers are bound in excitons. We suggest to use the exciton drag for fabrication of DC transformer. Preliminary estimates for Si/SiO2/Si structure give the Mott transition temperature of the order of 100 K. 相似文献