Study of New Ground and Excited States in Quantum Spin Systems under Extreme Conditions

极端条件下量子自旋系统新基态和激发态的研究

• 批准号: 20244056
• 负责人: TANAKA Hidekazu
• 金额: $ 16.81万
• 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 (A)
• 财政年份: 2008
• 资助国家: 日本
• 起止时间: 2008 至 2010
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-20244056/
• 关键词: 磁性; 量子スピン系; 強磁場; ボース凝縮; 量子相転移; フラストレーション; 物性実験; 低温物性; 強磁場物性; 高圧物性

From the analysis of the phase transition data obtained from specific heat measurement and the lineshape of the ESR spectrum for Tl_<1-x>K_xCuCl_3, we found that the field-induced quantum phase transition is the Bose glass (BG) to BEC transition of triplons and that the critical behavior for the temperature dependence of the transition field is described by the small-exponent characteristic of the BG-BEC transition. Using high-frequency high field ESR, we investigated elementary excitations of a quantum sine-Gordon (SG) spin system KCuGaF_6. We observed many resonance modes including a soliton resonance and breathers up to the third order, which are main elementary excitations characteristic of the quantum SG model. We found that their resonance conditions are beautifully described by the quantum SG field theory. We developed spin 1/2 kagome antiferromagnets Rb_2Cu_3SnF_<12> and Cs_2Cu_3SnF_<12>. We found that the ground state of Rb_2Cu_3SnF_<12> is a spin singlet with an excitation gap. Using inelastic neutron scattering experiments, we observed that a pinwheel valence-bond-solid state is realized in the ground state.

通过对比热测量获得的相变数据和Tl_<1-x>K_xCuCl_3的ESR谱线形的分析，我们发现场致量子相变是Bose玻璃（BG）到BEC的转变。三元组，并且过渡场温度依赖性的关键行为由 BG-BEC 过渡的小指数特征描述。使用高频高场 ESR，我们研究了量子正弦戈登 (SG) 自旋系统 KCuGaF_6 的基本激发。我们观察到许多共振模式，包括孤子共振和三阶呼吸，它们是量子 SG 模型的主要基本激发特征。我们发现量子 SG 场论完美地描述了它们的共振条件。我们开发了自旋1/2 kagome反铁磁体Rb_2Cu_3SnF_<12>和Cs_2Cu_3SnF_<12>。我们发现Rb_2Cu_3SnF_<12>的基态是具有激发间隙的自旋单线态。通过非弹性中子散射实验，我们观察到在基态下实现了风车价键固态。

项目成果

Observation of Elementary Excitations of Quantum Sine-Gordon Spin System KCuGaF_6 Under High Magnetic Field

强磁场下量子正弦戈登自旋体系KCuGaF_6初等激发的观察

• 发表时间: 2009
• 期刊: J.Low Temp.Phys. 159
• 作者: Y. Hatakeyama;T. Torimoto;S. Kuwabata;K. Nishikawa;S. Nakatsuji;松田康弘;久我健太郎;I.Umegaki
• 通讯作者: I.Umegaki

Evidence for continouos change of spin states between impurity-induced order and pressure-induced order in TlCu_<0.985>Mg_<0.015>Cl_3 probed via muon spin rotation

通过μ子自旋旋转探测TlCu_<0.985>Mg_<0.015>Cl_3中自旋态在杂质诱导有序和压力诱导有序之间连续变化的证据

• 发表时间: 2009
• 期刊: Phys.Rev.B 80
• 作者: T.Suzuki;I.Watanabe;F.Yamada;H.Tanaka;他
• 通讯作者: 他

一次元量子sine-Gordonスピン系KCuGaF_6の磁気比熱と量子効果

一维量子正弦-戈登自旋体系KCuGaF_6的磁比热和量子效应

• 发表时间: 2009
• 作者: 梅垣いづみ;小野俊雄;田中秀数
• 通讯作者: 田中秀数

Effect of electron localization on the edge-state spins in a disordered network of nanographene sheets

• DOI: 10.1103/physrevb.81.115408
• 发表时间: 2010-03-01
• 期刊: PHYSICAL REVIEW B
• 影响因子: 3.7
• 作者: Joly, V. L. Joseph;Takahara, Katsunori;Tanaka, Hidekazu
• 通讯作者: Tanaka, Hidekazu

ファラデー回転によるS=1/2カゴメ格子反強磁性体の一巻きコイル超強磁場磁化測定

利用法拉第旋转测量S=1/2 kagome晶格反铁磁材料一匝线圈的超强磁场磁化强度

• 发表时间: 2010
• 作者: 小野俊雄;宮田敦彦;嶽山正二郎;ソニアシャーミン;田中秀数
• 通讯作者: 田中秀数