FIELD-INDUCED NEW QUANTUM PHENOMENA IN MAGNETIC SYSTEMS

磁系统中场引发的新量子现象

• 批准号: 13130101
• 负责人: TANAKA Hidekazu
• 金额: $ 18.05万
• 依托单位: TOKYO INSTITUTE OF TECHNOLOGY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research on Priority Areas
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13130101/
• 关键词: Magnetism; Experiments for Solid State Physics; Low Temperature Physics; Statistical Mechanics; High Magnetic Field; Quantum Spin Systems; Field-Induced Magnetic Phenomena; Low Dimensional Magnets; 強磁場物性; 高圧物性; スピンギャップ; 量子相転移; 量子効果; 新物質; フラス

We have developed many quantum magnets, which have various crystal structures, and have investigated their magnetic properties in high magnetic fields. Followings are representative results. Coupled S=1/2 spin dimer systems undergo novel quantum phase transitions in high magnetic fields. These systems often have singlet ground states with excitation gaps. In high magnetic field, one of the triplets whose energy decreases with magnetic field plays an important role. The triplet can hop to neighboring site as a quasi-particle and interact due to the transverse and longitudinal components of the interdimer exchange interaction. The quasi-particle has characteristics of boson and is called magnon or triplon. Consequently, the system can be described as interaction boson system, where magnetic field corresponds to the chemical potential. We found that the magnetization plateaus in SrCu_2(BO_3)_2 and other systems. The magnetization plateau can occur when the hopping of magnons are strongly … More suppressed due to spin frustration or parity and the periodic arrangement of magnons (Wigner crystal) are stabilized due to the repulsive interaction. This is a typical quantum many-body effect By means of NMR in high magnetic fields on SrCu_2(B0_3)_2, we verify the realization of Wigner crystal of magnons. On the other hand, the field-induced antiferromagnetic (AF) ordering occurs when the hopping of magnons is dominant The ordering can be described as the Bose-Einstein condensation (BEC) of magnons. We have performed various measurements on the field-induced AF ordering in TlCuCl_3. Together with theoretical analysis, we verify that the field-induced AF ordering in TlCuCl_3 is the BEC of magnons. The present study demonstrated that there are cases where the quantum magnets exhibit the nature characteristic of ensemble of quantum particles. This provides a new concept of magnetism.To encourage our research project, we organized three open symposiums inviting researchers from abroad and International Symposium on Quantum Spin Systems QSS04. We also supported three international meetings. Less

我们已经开发了许多具有各种晶体结构的量子磁铁，并研究了它们在高磁场中的磁性。以下是代表性结果。耦合s = 1/2旋转二聚体系统在高磁场中的Novel量子相变。这些系统通常具有刺激差距的单线基态。在高磁场中，其中一个用磁场降低的三胞胎起着重要作用。三胞胎可以以准粒子的形式跳到相邻的位点，并由于互换相互作用的横向和纵向成分而相互作用。准粒子具有玻色子的特征，称为Magneton或三位。因此，该系统可以描述为相互作用的玻色子系统，其中磁场对应于化学电位。我们发现SRCU_2（BO_3）_2和其他系统中的磁化高原。当镁的跳跃强烈……由于旋转挫败或平等而受到​​抑制，并且由于排斥相互作用而稳定了镁（Wigner Crystal）时，可能会发生磁化高原。这是典型的量子多体效应，通过NMR在SRCU_2（B0_3）_2上的高磁场中，我们验证了镁质的Wigner晶体的实现。另一方面，当磁蛋白的跳跃占主导地位时，就会发生野外诱导的抗磁性（AF）排序，可以将订购称为镁的Bose-Einstein凝结（BEC）。我们在TLCUCL_3中对现场诱导的AF排序进行了各种测量。与理论分析一起，我们验证了tlcucl_3中的现场诱导的AF顺序是镁的BEC。本研究表明，在某些情况下，量子磁铁表现出量子颗粒集合的性质特征。这提供了一个新的磁性概念。为了鼓励我们的研究项目，我们组织了来自国外的三个开放研讨会邀请研究人员和国际量子旋转系统QSS04的国际研讨会。我们还支持三次国际会议。较少的