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1.
Spin-flip (paramagnetic) scattering and neutron depolarization studies were performed on Ce2Fe17 in its paramagnetic phase on the Dhruva neutron polarization analysis spectrometer. The absence of normalQ dependence of the scattered spin flip intensity shows that Ce2Fe17 is not a normal paramagnetic and there exist superparamagnetic clusters of sufficiently large dimensions (~100Å). The observed neutron depolarization gives an indication of the dynamics of these Ce2Fe17 superparamagnetic clusters. 相似文献
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Kenji Handa 《Journal of statistical physics》1996,83(3-4):555-571
Entropy production per site in a (nonreversible) spin-flip process is studied. We give it a useful expression, from which a property stronger than affinity of the entropy production per site follows. Furthermore, quasi-invariance of nonequilibrium measures in the spin-flip processes is discussed via entropy production. 相似文献
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The reduced adiabatic hyperspherical (RAHS) basis suggested previously is used for the calculation of elastic and spin-flip
cross sections in the processes (aμ)
F
+ a → (aμ)
F′ + a, a = (p,
d,
t), for collision energies 10−3 ≤ ε ≤ 102 eV. The rapid convergence of the method is demonstrated. A comparison of the obtained results with previous ones is presented.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
研究了与磁场强度相关的手性丙氨酸晶体的电子轨道运动的磁性质. 根据丙氨酸单晶的两性离子(+NH3-C(CH3)H-CO2-)模型的手性和蛋白质中肽键晶格结构的螺旋性, 当外加磁场为5 T, 磁场方向平行于丙氨酸晶轴(c)的极性N+H…O-氢键, 观察到D-丙氨酸晶格中, 氢原子的电子自旋翻转, 在297.6 K直接突现顺磁性. L-丙氨酸则先发生电子自旋转向, 然后在303.9 K突现顺磁性. 实验发现: 外加强磁场可以分裂手性丙氨酸晶格中氢键的简并顺磁态, 并测出能差. 本文进一步证明了准一维极性N+H…O-氢键在晶格中可以发生自旋-轨道分离, 表现出一维物理的基本特征. 相似文献
6.
It was first proposed that an extended chain Ising (ECI) model contains the Ising chain model, single spin double-well potentials and a pure phonon heat bath of a specific energy exchange with the spins. The extension method is easy to apply to high dimensional cases. Then the single spin-flip probability (rate) of the ECI model is deduced based on the Boltzmann principle and general statistical principles of independent events and the model is simplified to an extended chain Glauber-Ising (ECGI) model. Moreover, the relaxation dynamics of the ECGI model were simulated by the Monte Carlo method and a comparison with the predictions of the special chain Glauber-Ising (SCGI) model was presented. It was found that the results of the two models are consistent with each other when the Ising chain length is large enough and temperature is relative low, which is the most valuable case of the model applications. These show that the ECI model will provide a firm physical base for the widely used single spin-flip rate proposed by Glauber and a possible route to obtain the single spin-flip rate of other form and even the multi-spin-flip rate. 相似文献
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Saikiran Kotaru Sven Kähler Maristella Alessio Anna I. Krylov 《Journal of computational chemistry》2023,44(3):367-380
Low-energy spectra of single-molecule magnets (SMMs) are often described by Heisenberg Hamiltonians. Within this formalism, exchange interactions between magnetic centers determine the ground-state multiplicity and energy separation between the ground and excited states. In this contribution, we extract exchange coupling constants (J) for a set of iron (III) binuclear and tetranuclear complexes from all-electron calculations using non-collinear spin-flip time-dependent density functional theory (NC-SF-TDDFT). For 12 binuclear complexes with J-values ranging from −6 to −132 cm−1, our benchmark calculations using the short-range hybrid ωPBEh functional and 6-31G(d,p) basis set agree well with the experimentally derived values (mean absolute error of 4.7 cm−1). For the tetranuclear SMMs, the computed J constants are within 6 cm−1 from the experimentally derived values. We explore the range of applicability of the Heisenberg model by analyzing bonding patterns in these Fe(III) complexes using natural orbitals (NO), their occupations, and the number of effectively unpaired electrons. The results illustrate the efficiency of the spin-flip protocol for computing the exchange couplings and the utility of the NO analysis in assessing the validity of effective spin Hamiltonians. 相似文献
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考虑到铁磁层中的自旋极化效应、以及界面的粗糙散射和自旋反转效应,利用推广了的Blonder Tinkham Klapwijk理论模型,计算铁磁d波超导结中的自旋极化隧道谱.研究表明1)自旋反转效应能使零偏压电导峰变得尖锐;2)粗糙的界面散射除了能压低零偏压电导峰的高度,还能使零偏压凹陷处感应出一中心峰.结果能定性地解释最近的两篇关于La2/3Ba1/3 MnO3/DyBa2Cu3O7
关键词:
自旋极化效应
自旋反转效应
粗糙界面散射效应
隧道谱 相似文献
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手性丙氨酸单晶的极性N+H…O氢键在~270 K的自发对称性破缺, 可用变温拉曼振动光谱在b(cc)b几何条件下在线测定. 由于其对手性的灵敏度, 可以测定D-和L-丙氨酸的N+H…O氢键在电子自旋翻转相变时的微小能差. 晶体定向能量的正/负, 在于电子自旋的上/下转向, 取决于原子内在磁场的方向. 变温拉曼振动光谱可以观察到: 在D-和L-丙氨酸单晶之间, 拉曼散射光子的波数位移方向相反, 散射光子的不对称度约为1/3. 由于自旋是轴矢量, 样品必须是单晶, 沿轴向测定. 多晶粉末不能观察到相变. 与次甲基(Cα-H)在260 K的自旋翻转相变, 用变温拉曼振动光谱在c(aa)c 几何条件下的相对测量结果接近一致. 本实验提供了一条证明真实手性和“宇称-时间(PT)不对称”的新线索. 相似文献