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

在本项目中，我们对自旋S=1的准一维海森堡反铁磁体Ni（C_5H_N_2<14>）_2N_3（PF_6）（简称NDMAP）进行了实验研究，并发现了它的场诱导磁性长程有序（LRO）。从磁化强度的温度和磁场依赖性，我们得到了信息的自旋排列在有序相。也就是说，在低温和高磁场下，自旋被限制在c平面内，并且方向垂直于外场。从电子自旋共振（ESR）测量NDMAP，我们观察到两种信号在低温和高磁场，其中之一对应于反铁磁共振和其他的一维激发。这一发现为理解S=1的Q1 D反铁磁体的磁激发提供了新的认识。我们还测量了氘化单粒子上的中子散射 ...更多信息 晶体的NDMAP，并发现布拉格峰在（0，1/2，1/2）点，从而证实了场诱导的LRO确实存在。与理论物理学家合作，分析了NDMAP的磁场-温度相图，计算了S= 1的一维系统与单离子snisotropy考虑链间耦合的影响，作为一个平均场的形式。我们用脉冲中子源测量了La_6Ca_8Cu_O_3梯形部分的磁激发<24><41>。我们成功地观察到一个完整的分散曲线的低能量激发的阶梯。通过对数据的分析，我们发现，要得到一个合理的结果，需要一个四自旋相互作用，其中约有10%的主导相互作用（腿和梯子）。除此之外，我们还研究了几个量子磁体，并获得了新的结果，详细情况在小册子中报道。少

项目成果

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。

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)

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）。

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, 13. 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, 13. 9272-9274 (1999)