The Physics and Chemistry of Quantum Magnetism

量子磁学物理与化学

• 批准号: 11694110
• 负责人: KATSUMATA Koichi
• 金额: $ 8.83万
• 依托单位: RIKEN, The Institute of Physical and Chemical Research
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A).
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11694110/
• 关键词: Quantum magnet; Quasi-one-dimensional antiferromagnet; Haldane effects; Spin-ladder; Field-induced phase transition; ESR; Magnetization process; Magnetic excitation

In this project, we have performed several experimental studies on the spin, S=1 quasi-one-dimensional(Q1D) Heisenberg antiferromagnet Ni(C_5H_<14>N_2)_2N_3(PF_6)(abbreviated NDMAP) for which a field induced magnetic long range ordering (LRO)has been discovered by the present investigator and co-workers. From the temparature and magnetic field dependence of the magnetization, we got information on the spin arrangement in the ordered phase. Namely, at low temperature and high magnetic fields, spins are confined in the c plane and directed perpendicular to the external field. From electron spin resonance(ESR)measurements on NDMAP, we observed two kinds of signals at low temperature and high magnetic field, one of which corresponds to an antiferromagnetic resonance and the other to a one-dimensional excitation. This finding Provides a new knowledge towards the understanding of magnetic excitation in an S=1 Q1D antiferromagnet. We have also measured neutron scattering on deuterated single … More crystals of NDMAP and found a Bragg peak at(0, 1/2, 1/2)point associated with the long range magnetic ordering at high field and low temperature, thus confirming that the field unduced LRO really exists.In collaboration with theoretical physicists, we have analyzed the magnetic field versus temperature phase diagram of NDMAP.We calculated the staggered susceptibility of S=1 one dimensional system with a single ion snisotropy taking into account the effects of the inter-chain couplings as the form of a mean-field. The theoretical result well reproduces the experimental phase diagram obtained by us.We have measured the magnetic excitations from the ladder part of La_6Ca_8Cu_<24>O_<41> using a pulsed neutron source. We were successful in observing a full dispersion curve for the low energy excitation in the ladder. From the analysis of the data, we found that a four spin interaction with about 10% of the dominant interactions(leg and ladder) is necessary to get a reasonable result.In addition to these, we have studied several quantum magnets and obtained new results, details of which are reported in the booklet. Less

在这个项目中，我们已经对旋转进行了几项实验研究，S = 1个Quasi二维（Q1D）Heisenberg Antiferromagnet Ni（C_5H_ <14> n_2）_2N_3（PF_6）（PF_6）（pf_6）（pf_6）（缩写NDMAP），该磁场诱导了磁性磁性长距离订单（lro）被发现的仪式（lro）被发现了。从磁化强度的温度和磁场依赖性中，我们在有序阶段获得了有关自旋布置的信息。也就是说，在低温和高磁场下，旋转被限制在C平面中，并垂直于外场。从NDMAP上的电子自旋共振（ESR）测量中，我们在低温和高磁场下观察到两种信号，其中一个对应于抗磁共振共振，另一个对应于一维兴奋。这一发现为理解s = 1 Q1D抗fiferromagnet中的磁兴奋提供了新的知识。我们还测量了在氘化的单个……更多的NDMAP晶体上的中子散射，并在（0、1/2、1/2）点处达到了与高场和低温下的远距离磁有序相关的（0、1/2、1/2）点，从而证实了该领域的LRO确实存在。 S = 1具有单个离子Snisotropy的一个维系统，考虑到链间耦合作为平均场的形式。理论结果很好地重现了我们获得的实验相图。我们使用脉冲中子源测量了La_6ca_8cu_ <24> o_ <41>的磁兴奋。通过数据分析，我们成功地观察了低能的完整分散曲线，我们发现，有大约10％的主要相互作用（腿和梯子）的四个自旋相互作用是为了获得合理的结果。在此外，我们研究了几种量子磁铁并获得了新的结​​果，并在手册中报道了这些结果。较少的

项目成果

本多善太郎: "Coexistence of one-and three-dimensional excitations in a quasi-one-dimensional S=1 Heisenberg antiferromagnet"Phys.Rev.B. 60. 9272-9274 (1999)

Zentaro Honda：“准一维 S=1 海森堡反铁磁体中一维和三维激发的共存”Phys.Rev.B. 60. 9272-9274 (1999)

Z.Honda et al.: "Coexistence of One-and Three-Demensional Excitations in a Quasi-One-Dimentional S=1 Heisenberg Antiferromagnet"Phys. Rev. B. 60, 13. 9272-9274 (1999)

Z.Honda 等人：“准一维 S=1 海森堡反铁磁体中一维和三维激励的共存”Phys。

松田雅昌: "Magnetic excitations in the S=1/2 quasi-one-dimensional magnet Sr_<14-x>Ca_xCu_<24>O_<41>"J.Appl.Phys.. 85. 5642-5644 (1999)

松田正正：“S=1/2 准一维磁体 Sr_<14-x>Ca_xCu_<24>O_<41> 中的磁激励”J.Appl.Phys.. 85. 5642-5644 (1999)

松田雅昌: "Magnetic excitations from the S=1/2 two-leg ladders in La_6Ca_8Cu_<24>O_<41>"J.Appl.Phys.. (印刷中). (2000)

Masamasa Matsuda：“La_6Ca_8Cu_<24>O_<41> 中 S=1/2 两腿梯子的磁激发”J.Appl.Phys..（出版中）。

萩原政幸: "Magnetization process of the S=1/2 and 1 Ferrimagnetic Chain and Dimer"J.Phys.Soc.Jpn.. 68,7. 2214-2217 (1999)

Masayuki Hagiwara：“S=1/2 和 1 亚铁磁链和二聚体的磁化过程”J.Phys.Soc.Jpn.. 68,7 (1999)。