权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Mechanism of magnetization induction and its dynamics in strongly correlated quantum spin systems

强相关量子自旋系统中的磁化感应机制及其动力学

基本信息

批准号：
12640368
负责人：
MIYASHITA Seiji
金额：
$ 2.43万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640368/
关键词：
Quantum Spin Systems Non-adiabatic transition Quantum Dynamics Spin Peierls transition Quantum computing Electron Spin Resonance 不純物誘起磁化光誘起相転移スピンパイエルス相転移 ESR

项目摘要

We have studied novel characteristics inherent to quantum mechanical effects in quantum spin systems, and investigated their mechanics. In particular, we mainly studied the properties of one dimensional Heisenberg models. One of the topics is the effect of spatial inhomogeneity. We clarified the temperature dependence of the magnetization profile at the edges of the lattice and also the inhomogeneity-induced magnetization at defect of the alternation in bond-alternate Heisenberg models. These magnetization can be regarded asan isolated magnetization, and we also studied the quantum dynamics of the magnetization in the sweeping field. We also studied the electron spin resonance (ESR) in strongly correlated spin systems. We found that the coexistence of so-called antiferromagnetic resonance and the paramagnetic resonance in antiferromagnetic cluster. Temperature dependence of the shift of the resonant position was also studied on the ladder system. The ordering process of spin-Peierls transition was also studied by quantum Monte Carlo simulation where we show how the bond-alternation develops as the temperature decreases. We found large amount of the fluctuation at high temperatures which cause the deviation of the susceptibility from the Bonner-Fisher's curve. We extend the study to the case of S=1 where the spin-Peierls transition takes place between the Haldane state and the bond-alternating state. We found the transition is of the first order and obtained the shape of the domain wall between the two nonmagnetic states.The noise effects on the quantum mechanical dynamics of nanoscale molecular magnets were extensively studied and we proposed the noise induced square-root time behavior and also a mechanism of magnetization plateau due to small inflow of the heat in the adiabatic process (magnetic Feohn effect).

我们研究了量子自旋系统中量子力学效应所固有的新特性，并研究了它们的力学性质。特别是，我们主要研究了一维Heisenberg模型的性质。其中一个主题是空间不均质性的影响。我们阐明了晶格边缘磁化强度分布的温度依赖性，以及键交替海森堡模型中缺陷处的非均匀感应磁化强度。这些磁化可以看作是孤立磁化，我们还研究了扫描场中磁化的量子动力学。我们还研究了强关联自旋系统中的电子自旋共振(ESR)。我们发现在反铁磁团簇中存在所谓的反铁磁共振和顺磁共振的共存。在梯形系统上还研究了共振位置漂移与温度的关系。用量子蒙特卡罗模拟方法研究了自旋-Peierls相变的有序化过程，给出了随温度降低键变的发展过程。我们发现在高温下有大量的波动，导致磁化率偏离Bonner-Fisher曲线。我们将研究推广到S=1的情形，其中自旋-Peierls相变发生在霍尔丹态和键交替态之间。研究了噪声对纳米分子磁体量子力学动力学的影响，提出了噪声诱导的平方根时间行为，以及绝热过程中小能量流入导致磁化平台的机制(磁Feohn效应)。