Quantum Phase Transition of Triangular Spin Tube

三角形自旋管的量子相变

• 批准号: 18340096
• 负责人: NOJIRI Hiroyuki
• 金额: $ 10.62万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2006
• 资助国家: 日本
• 起止时间: 2006 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18340096/
• 关键词: Chirality; Quantum Spin; Quantum Phase Transition; Ultra-low temperature; High Magnetic Field; Molecular Magnet

The purpose of the research is to investigate the magnetic excitation and the quantum phase transition of a triangular spin nano-tube:[CuCl_2tachH]_3Cl]Cl_2:the first quantum spin tube found by us. In the specific heat at ultra-low temperature, we found complex excitations made of two components. The first one is a gapped excitation, which can be fitted by an Ising chain model. The second one is a gap-less excitation with a small density of state. The result indicates that two types of excitations coexist in a spin tube. The origin of the gapped excitation is the excitation of spin chirality holding the Ising nature. This may be associated with the ordering of spin chirality at low temperature. The second excitation is caused by a spin wave like excitation, however, the fraction of this is only 25 % or less of that of a spin chain. It shows that the ground state of the present spin tube is gapless with considerable renormalization of energy.To investigate the phase diagram of spin tube, we made a D-substituted sample and succeeded in modulating the exchange coupling in the chain direction. It is found that the exchange coupling in increased by 7 % by D-substitution. The origin of the modulation is the suppression of proton tunneling in hydrogen bonds connecting neighboring triangles in chain direction. In NMR, no magnetic anomaly is found down to very low temperature and the good separation between the tubes are confirmed.The present investigation indicates the variety of magnetic properties in a quantum spin tube, which is caused by the existence of two degrees of freedom: spin and spin chirality.

本文研究了三角形自旋纳米管[CuCl_2tachH]_3Cl]Cl_2的磁激发和量子相变。在超低温比热中，我们发现了由两个分量组成的复杂激发。第一种是带隙激励，可以用伊辛链模型拟合。第二种是具有小态密度的无隙激发。结果表明，两种激励在旋转管内共存。带隙激发的起源是自旋手征的激发，具有伊辛性质。这可能与低温下自旋手征的有序性有关。第二激发是由自旋波类激发引起的，然而，其分数仅为自旋链的分数的25%或更少。为了研究自旋管的相图，我们制作了一个D取代的样品，并成功地在链方向上调制了交换耦合。发现D-取代使交换耦合增加了7%。调制的起源是在链方向上连接相邻三角形的氢键中质子隧穿的抑制。在核磁共振中，在很低的温度下没有发现磁异常，并且证实了量子自旋管之间的良好分离.本文的研究表明，量子自旋管中的磁性质的变化是由两个自由度的存在引起的：自旋和自旋手征.

项目成果

^1HNMR of spin tube [CuCl_2tachH]_3Cl]Cl_2

旋转管的^1HNMR [CuCl_2tachH]_3Cl]Cl_2

• 发表时间: 2007
• 作者: H. Murakawa;K. Ishida;K. Kitagawa;H. Ikeda;Z. Q. Mao;and Y. Maeno;Y. Sumida
• 通讯作者: Y. Sumida

三角スピンチューブ[CuCl_2tachH]_3Cl]Cl_2の1HNMR

三角旋转管[CuCl_2tachH]_3Cl]Cl_2的1HNMR

• 发表时间: 2007
• 作者: K.;Ishida;Y.;Ihara;H.;Takeya;C.;Michioka;K.;Yoshimura;K.;Takada;T.;Sasalci;H.;Salcurai;E.;Takayama-Muromachi;Yutaka Maniwa;住田 譲
• 通讯作者: 住田 譲

NMR STUDIES OF SPIN DYMANICS IN NANOSCALE MOLECULAR MAGNET V15 AT VERY LOVE TEMPERATURE

非常热温度下纳米级分子磁体 V15 中自旋动力学的核磁共振研究

• 发表时间: 2006
• 作者: 宮田耕充;柳和宏;真庭豊;片浦弘道;Y. Furukawa
• 通讯作者: Y. Furukawa

^H-NMR Studies of Quantum Spin Chain System (CH_3)_2NH_2CuCl_3 at Very Low Temperature

^超低温量子自旋链体系(CH_3)_2NH_2CuCl_3的H-NMR研究

• 发表时间: 2006
• 作者: S. Kimura;T. Ito;H. Miyazaki;T. Mizuno;T. Iizuka;T. Takahashi;Y. Furukawa
• 通讯作者: Y. Furukawa

Local spin moment distribution in molecular nanomagnets determined by NMR

通过 NMR 测定分子纳米磁体中的局部自旋矩分布

• 发表时间: 2007
• 作者: T. Nakajima;H. Mitamura;Y. Ueda;Y. Furukawa;Y. Furukawa
• 通讯作者: Y. Furukawa