Dynamics of low dimensional quantum spin systems and effects of carrier doping.

低维量子自旋系统的动力学和载流子掺杂的影响。

• 批准号: 10304027
• 负责人: TAKIGAWA Masashi
• 金额: $ 23.55万
• 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 (A)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10304027/
• 关键词: Quantum Spin System; Nuclear Magnetic Resonance; Carrier Doping; Spin Gap; Low Dimensionality; 梯子格子; 近藤絶縁体; ホールドープ; 電荷ゆらぎ; 電荷凍結; 近藤半導体; スピン拡散; 高温超伝導

Since the high temperature superconductivity was discovered in 1986, various attempts were made to dope carriers into low dimensional quantum spin systems, which are the Mott-insulators and to find superconductivity. In such a trend of research, the first objectives of this project was set to clarify the dynamics of the low dimensional quantum spin systems from a microscopic point of view using nuclear magnetic resonance as the principal tool. Second objective was to understand the change in magnetic dynamics upon elemental substitution or doping carriers or impurities. The former was achieved by the experiments on the hole-doped spin-ladder materials and the two-dimensional orthogonal dimer spin systems, which yielded variety of different behavior of spin excitations for the singket ground state. Concerning the latter, experiments on hole-doped ladder materials have shown that interaction between carriers and the magnetic excitations induces paring of holes. The thermally depaired carriers are shown to cause significant damping of magnetic excitations. Furthermore, extremely slow charge fluctuations associated with partial charge ordering were observed in a few quasi-one-dimensional conducting systems. On the other hand, in Kondo insulators, which is another example of spin gap material, we found that local moments are induced near impurities similar to the case of quantum spin systems.

由于在1986年发现了高温超导性，因此已尝试将各种尝试掺入低维量子自旋系统，这些量子自旋系统是莫特的构造剂，并找到了超导性。在这样的研​​究趋势中，该项目的第一个目标是从微观的角度阐明低维量子自旋系统的动力学，使用核磁共振作为主要工具。第二个目标是了解元素取代或掺杂载体或杂质时磁化动力学的变化。前者是通过实验在孔掺杂的旋转液体材料和二维正交二聚体自旋系统上实现的，该系统产生了单孔基态的自旋激发的各种不同行为。关于后者，对孔掺杂的梯子材料进行的实验表明，载体与磁激发之间的相互作用会引起孔的削皮。显示热载体会引起磁激发的严重阻尼。此外，在几个准二维导电系统中观察到与部分电荷顺序相关的极慢电荷波动。另一方面，在Kondo绝缘子中，这是自旋差距材料的另一个例子，我们发现局部矩与量子自旋系统相似的杂质几乎诱导的杂质。

项目成果

陰山 洋: "Exact Dimen Ground State and Quantized Magnelization Plateaus in the Two-Dimensional Spin System SrCn_2(Bo_3)_2"The Physical Review Letters. 82・15. 3168-3171 (1999)

Hiroshi Kageyama：“二维自旋系统 SrCn_2(Bo_3)_2 中的精确维门基态和量子化磁化平台”物理评论快报 82・15 (1999)。

K. Ohwada: "Devil's Staicase-Type Phase Transition in NaV_20_5 under High Pressure"Phys. Rev. Lett.. 87. 086402-1-4 (2001)

K. Ohwada：“高压下 NaV_20_5 中的魔鬼型相变”Phys。

O. Vyaselev: "Lattice Distortion and First Order Transition in TlCuCl_3"Proceedings of Japanese-French Seminar. (in press).

O. Vyaselev：“TlCuCl_3 中的晶格畸变和一阶跃迁”日法研讨会论文集。

D.Akahoshi: "Oxygen Nonstoichiometry, Structures, and Physical Properties of YbaCo_2O_<5+x>(0.00 x 0.52)"J. Solid State Chem.. 156. 355-363 (2001)

D.Akahoshi：“YbaCo_2O_<5 x>(0.00 x 0.52) 的氧非化学计量、结构和物理性质”J。

Shigeki FUJIYAMA: "Nuclear Spin Relaxation in Hole-Doped Two-Leg Ladders"J.Phys.Soc.Japan. 69.No 6. 1610-1613 (2000)

Shigeki FUJIYAMA：“掺孔两腿梯中的核自旋弛豫”J.Phys.Soc.Japan。