共查询到20条相似文献,搜索用时 15 毫秒
1.
O. M. Al-Dossary 《International Journal of Theoretical Physics》2010,49(6):1187-1194
The energy levels structure of two interacting electrons in a parabolic quantum dot under an external magnetic field of arbitrary
strength is studied via the asymptotic iteration method. The method gives accurate results over the full range of quantum
dot parameters. A crossings between spin-singlet and spin-triplet ground states energies as a function of the magnetic field
is predicted. 相似文献
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采用局域Monte Carlo方法模拟不同易轴分布的简单立方排列单分散单畴Fe纳米颗粒系统的ZFC-FC曲线及磁滞回线.结果表明:随着偶极相互作用的增强,系统的阻塞温度TB逐渐增大,且ZFC曲线的峰变宽.说明偶极相互作用使得系统的有效能垒提高,分布宽度增加.研究FC曲线磁化强度的倒数与温度关系,发现偶极相互作用系统中存在反铁磁有序.系统的阻塞态及超顺磁态的磁滞回线表明,极低低温下,随着偶极相互作用的增强,系统的矫顽力和剩磁减小,偶极相互作用阻碍系统的磁化;系统处于超顺磁态,各向异性作用及偶极相互作用使得系统的磁化曲线偏离Langevin曲线且偶极相互作用展现出退磁相互作用效应.偶极相互作用增强,系统磁化曲线与Langevin曲线偏差量的最大值向低场移动.在偶极相互作用下,易轴与外场夹角为45°的磁性纳米颗粒系统的平均有效能垒和有效能垒分布宽度较易轴随机分布系统的大. 相似文献
3.
International Journal of Theoretical Physics - The ground state phases of spin-1 Bose-Einstein condensates with Rashba spin-orbit coupled (SOC) and dipole-dipole interaction (DDI) are studied.... 相似文献
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The mechanism of excitation and propagation of spin waves in Ge: Mn thin films with different nominal manganese concentrations (2, 4, and 8 at % Mn) with percolation magnetic ordering is explored. Concentration dependencies of Curie temperature TC(n) and spin wave rigidity D(n) are determined, which enables to find the index of correlation distance. An exotic percolation magnetic state of samples of Ge: Mn thin films is confirmed by rectifying experimental dependences D(n) and D/TC(n) in coordinates accepted in the percolation theory. 相似文献
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We have investigated the dipole interaction energies per particle and the local dipole field distributions in a frozen-magnetization model of a ferrofluid chain in a saturating magnetic field. A lognormal distribution of particle diameters was assumed. The interaction energies were calculated for one-dimensional arrays of dipoles with moments parallel to the chain. We have computed the energies by various approximations related to the hard sphere particle diameter distribution. A similar approach was followed for the local field distributions. It was found that the energy per particle and mean local field were largely determined by the mean particle diameter, but the distribution of local fields was sensitive to both the mean diameter and the assumptions about spatial correlations between particles of different size. Detailed results are presented for water-soluble Fe3O4/PAA (polyacrylic acid). 相似文献
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Physics of the Solid State - The ground state of a classical two-sublattice ferromagnet with the noncollinear single-ion anisotropy axes of the sublattices and the antisymmetric and anisotropic... 相似文献
9.
XIE Wen-Fang 《理论物理通讯》2008,49(3):763-766
In this paper, we study four electrons confined in a
parabolic quantum dot in the absence of magnetic field, by the exact
diagonalization method. The ground-state electronic structures and orbital
and spin angular momenta transitions as a function of the confined
strength are investigated. We find that the confinement may cause
accidental degeneracies between levels with different low-lying states and
the inversion of the energy values. The present results are useful to
understand the optical properties and internal electron-electron
correlations of quantum dot materials. 相似文献
10.
We consider a large atom with nuclear charge Z described by non-relativistic quantum mechanics with classical or quantized electromagnetic field. We prove that the absolute
ground state energy, allowing for minimizing over all possible self-generated electromagnetic fields, is given by the non-magnetic
Thomas-Fermi theory to leading order in the simultaneous Z → ∞, α → 0 limit if Z
α
2 ≤ κ for some universal κ, where α is the fine structure constant. 相似文献
11.
JETP Letters - Charge and orbital ordering, magnetic state, and exchange couplings in quasi-one-dimensional vanadate V6O13, a potential cathode material for Li-ion batteries, are investigated using... 相似文献
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An algorithm is proposed for deriving the position of a stable radical relative to a photoexcited quartet state from the electron spin–spin interactions measured by double resonance methods. Intersystem crossing generates multiplet polarization in the quartet state and microwave excitation of the ±3/2 ? ±1/2 transitions converts the multiplet polarization into net polarization of the ±1/2 levels. The dependence of the electron spin echo envelope modulation (ESEEM) of the +1/2 ? ?1/2 transition on the field/frequency of the stimulation pulse is demonstrated. The algorithm is tested by comparing the predicted ESEEM patterns to those from explicit numerical calculations of the spin evolution (so-called numerical experiments), which act as a model for experiment results. The comparison demonstrates that within the point-dipole approximation it is feasible to obtain not only the distance between the two paramagnetic centers but also the orientation of the distance vector relative to the principal axes of the quartet state. 相似文献
16.
The influence on the short-range packing in dipolar fluids by molecular shape and by additional higher order electrostatic
moments has been investigated by molecular dynamic simulations. The dipole polarization was found to decrease as the particles
were elongated parallel to the dipole and to increase for elongation perpendicular to the dipole, eventually forming a nematic
order. The addition of a quadrupole lead to a reduction of the polarization, and the influence of an axial octupole was weaker
and more complex. Both a decrease and an increase of the polarization is possible depending on the relative dipole–dipole
and octupole–octupole interaction strengths and the relative direction of the symmetry axes of the moments. These observations
were attributed to the different parity of a dipole and a quadrupole and the same parity of a dipole and an axial octupole
under reflection. In addition, further insights into the formation of dipole polarization were obtained. Short polar and long
equatorial radii and strong dipole–dipole interaction are particle properties that promote a fluid with a high dipole polarization. 相似文献
17.
利用固相反应法制备了名义成分为Ca(Mn2 Cu1 )Mn4 O1 2 的类钙钛矿锰氧化物 .x射线衍射表明 ,为了获得较为致密的样品和减小杂相含量 ,可以采用高温烧结再在 10 73K长时间空气中退火的制备方法 .样品在低温下同时存在铁磁相和反铁磁相 ,由于反铁磁相的存在导致样品在 4 5K时的磁化强度显著降低 ,并在 8T的高磁场下仍未达到饱和 .样品呈半导体导电性质 ,在 85K和 6T磁场下磁电阻比的最大值可达 - 4 6 % . 相似文献
18.
利用固相反应法制备了名义成分为Ca(Mn2Cu1)Mn4O12的类钙钛矿锰氧化物.x射线衍射表明,为了获得较为致密的样品和减小杂相含量,可以采用高温烧结再在1073K长时间空气中退火的制备方法.样品在低温下同时存在铁磁相和反铁磁相,由于反铁磁相的存在导致样品在4.5K时的磁化强度显著降低,并在8T的高磁场下仍未达到饱和.样品呈半导体导电性质,在85K和6T磁场下磁电阻比的最大值可达-46%.
关键词:
[AC3](B4)O12类钙钛矿锰氧化物
庞磁电阻效应
铁磁性
反铁磁性 相似文献
19.
Based on the exact and numerical calculations within the Ising and Potts models on lattices of various types and dimensions (one-dimensional, square, triangular, hexagonal, kagome, simple cubic, and body-centered cubic), magnetic orderings, phase transitions, and frustrations were investigated, taking into account the exchange interactions between magnetic moments at the nearest and next-nearest nodes and an external magnetic field. The causes of the occurrence of frustrations are found, and the essential features of the behavior of frustrated systems that distinguish them from the nonfrustrated systems are determined. 相似文献
20.
In addition to the well-known quantum numbers, the total spin as a good quantumnumber has also been introduced to classify the eigenstates of the H3+-like systems. Thedegeneracy of the ground state and the structures of the ground rotation bands have beendeduced based on an ab initio symmetry consideration. 相似文献