EFFECT OF RANDOMNESS OF EXCHANGE INTERACTIONS IN QUANTUM SPIN SYSTEMS WITH ENERGY GAP

具有能隙的量子自旋系统中交换相互作用随机性的影响

• 批准号: 13440118
• 负责人: YAMADA Isao
• 金额: $ 9.54万
• 依托单位: CHIBA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13440118/
• 关键词: Haldane state; singlet dimer state; bond randomness; alternating chain; (CH_3)_2CHNH_3CuCl_3; (CH_3)_2CHNH_3CuBr_3; dimer系

The isomorphous compouns (CH_3)CHNH_3CuCl_3 and (CH_3)_2CHNH_3CuBr_3 consists of ferromagnetic-ferromagnetic and aritiferromagnetic anatiferromagnetic alternating Heisenberg chains with S =1/2, respectively The magnetic ground state is therefore regarded as the Haldane state in the former and the singlet dimer state in the latter. To clarify the effect of bond randomness on the Haldane state as well as on the singlet dimer state, the magnetic state of the random alternating Heisenberg chains (CH_3)CHNH_3Cu(Gl_xBr_1-x)_3, I.e., mixed systems of The two compounds mentioned above, were investigated From magnetic susceptibility and specific heat measurements, it was confirmed that a gapless magnetic phase appeals over the intermediate region 0.44<x<0,87. At the two boundaries, I.e, the boundary between the Haldane phase and the gapless phase and that between the gapless phase and the singlet dimer phase, the energy gap abruptly becomes zero. This study clarified that bond randomness wipes but the energy gap in both the Haldane state and the singlet dimer state, when the strength of bond randomness exceeds a certain value. Measurements of magnetization process also showed the appearance of the energy gap over 0.44<x<0,87.

同构的组合（CH_3）CHNH_3CUCL_3和（CH_3）_2CHNH_3CUBR_3组成在后者。为了阐明键随机性对haldane状态以及对单二聚体状态的影响，随机交替交替的海森堡链（CH_3）CHNH_3CU（GL_XBR_1-X）_3，即，在上面提到的两种化合物的混合系统中，与特定的热度测量区域相比，研究了与特定的热量阶段有关的混合系统。 0.44 <x <0,87。在两个边界，即霍尔丹阶相和无间隙相之间的边界，以及无间隙相和单元二聚体相之间的边界，能量差距突然变为零。这项研究阐明了键随机性擦除，但是当键随机性的强度超过一定值时，haldane状态和单线二聚体状态的能量差距均在haldane状态下。磁化过程的测量还显示了能量间隙在0.44 <x <0,87上的外观。

项目成果

H.Manaka, I.Yamada, M.Hagiwara, M.Tokunaga: "High Field and High Frequency ESR Study of the Haldane State Formed in the Ferromagnetic and Antiferromagnetic Alternating Heisenberg Chain System (CH_3)_2CHNH_3CuCl_3"Phys.Rev.B. 63. 144428-1-144428-4 (2001)

H.Manaka、I.Yamada、M.Hagiwara、M.Tokunaga：“铁磁和反铁磁交替海森堡链系统 (CH_3)_2CHNH_3CuCl_3 中形成的霍尔烷态的高场和高频 ESR 研究”Phys.Rev.B。

H, Manaka: "Optical Birefringence Measurements in Ferromagnetic and Antiferromagnetic Alter- nating Heisenberg Chains (CH_3)_2CHNH_3CuCl_3"J. Phys. Soc. Jpn.. 70. 2509-2512 (2001)

H，Manaka：“铁磁和反铁磁交替海森堡链 (CH_3)_2CHNH_3CuCl_3 中的光学双折射测量”J。

J.Chakhalian, R.F.Kiefl, R.Miller, S.R.Dunsiger, G.Morris, S.Krietzman, W.A.MacFarlane, J.Sonier, S.Eggert, I.Affleck, I.Yamada: "Local Magnetic Susceptibility of the Positive Muon in the Quasi One-Dimensional S=1/2 Antiferromagnet KCuF_3"Physica B. 326.

J.Chakhalian、R.F.Kiefl、R.Miller、S.R.Dunsiger、G.Morris、S.Krietzman、W.A.MacFarlane、J.Sonier、S.Eggert、I.Affleck、I.Yamada：“正 μ 子的局部磁化率

A. Agul: "Resonant Ok a Emission Spectra of CuGeO_3 Single Crystal"Solid State Commun. 118. 619-622 (2001)

A. Agul：“CuGeO_3 单晶的发射光谱共振确定”固态通讯。

A.N.Vasil'ev, L.A.Ponomarenko, H.Manaka, I.Yamada, M.Isobe, Y.Ueda: "Magnetic and Resonant Properties of Quasi-One-Dimensional Antiferromagnet LiCuVO_4"Phys.Rev.B. 64. 024419-1-024419-5 (2001)

A.N.Vasilev、L.A.Ponomarenko、H.Manaka、I.Yamada、M.Isobe、Y.Ueda：“准一维反铁磁体 LiCuVO_4 的磁性和谐振特性”Phys.Rev.B。