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.

从比热测量获得的相变数据和Tl_&lt；1-x&Gt；K_xCuCl3的ESR谱线形分析，我们发现场致量子相变是三重子的玻色玻璃(BG)到BEC的相变，相变场随温度变化的临界行为用BG-BEC相变的小指数特性来描述。用高频高场ESR研究了量子Sine-Gordon(SG)自旋系统KCuGaF_6的基元激发。我们观察到了许多共振模式，包括孤子共振和高达三阶的呼吸子，这是量子SG模型的主要基元激发特征。我们发现量子SG场论很好地描述了它们的共振条件。我们研制了自旋为1/2的Kagome反铁磁体Rb_2Cu3SnF_(12)和Cs_2Cu3SnF_(12)。我们发现Rb_2Cu3SnF_12&gt；的基态是具有激发能隙的自旋单重态。利用非弹性中子散射实验，我们观察到在基态下实现了风轮价键固相。

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

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

Evidence for continuous 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

• DOI: 10.1103/physrevb.80.064407
• 发表时间: 2009
• 期刊: Phys. Rev
• 作者: Takao Suzuki;Isao Watanabe;Fumiko Yamada;Yasuyuki Ishii;Kazuki Ohishi;Risdiana;Takayuki Goto and Hidekazu Tanaka
• 通讯作者: Takayuki Goto and Hidekazu Tanaka

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

Bond-randomness effect on the quantum spin system Tl_<1-x> K_xCuCl_3 probed b y muon-spin-relaxation method

μ子自旋弛豫法探测量子自旋体系Tl_<1-x> K_xCuCl_3的键随机效应

• DOI: 10.1016/j.physb.2008.11.108
• 发表时间: 2009
• 期刊: Physica
• 作者: Takao Suzuki;Fumiko Yamada;Isao Watanabe;Takayuki Goto;Akira Oosawa and Hidekazu Tanaka
• 通讯作者: Akira Oosawa and Hidekazu Tanaka