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Investigations of new field induced quantum phenomena in magnetic systems by high field ESR and neutron diffraction measurements

通过高场 ESR 和中子衍射测量研究磁系统中新的场诱导量子现象

基本信息

批准号：
13130204
负责人：
OHTA Hitoshi
金额：
$ 74.18万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2004
项目状态：
已结题

项目摘要

New model substances for diamond chain, delta chain and zig-zag chain systems are found, and following new field induced quantum phenomena have been investigated.1) The model substance of diamond chain Cu_3(CO_3)_2(OH)_2 has been found for the first time. The magnetic susceptibility result shows two peaks and it suggests that two kinds of short range order exist in the system. Low temperature magnetization measurements show 1/3 magnetization plateau, which has been observed in the diamond chain model substance for the first time. The exchange interactions of Cu_3(CO_3)_2(OH)_2 are determined by analyzing the magnetization curve by the theory. High field ESR measurements of shows the dynamics of the system and the direct transition which changes at the magnetization plateau.2) The breather mode up to the saturation magnetization, the decrease of the field induce gap under the high field and the cross-over effect of the excited mode above the saturation field have been observed in the on … More e dimensional antiferromagnet Cu-benzoate. The breather mode is also observed in the one dimensional mixed crystal system BaCu_2(Si_<1-x>Gex)_2O_7.3) Two-triplet bound state is investigated in details for two dimensional dimer system SrCu_2(BO_3)_2.4) The magnetization plateau has been observed in the giant magnetic molecule for the first time, and the frustration effect in the system is discussed.5) High field ESR system under high pressure has been developed. The suppression of the spin gap under pressure at 4.2 K has been observed directly in the dimer system KCuCl_3 by observing the direct transition using our new high field ESR system under pressure up to 10 kbar.6) The fine energy structure of the finite Haldane chain system has been investigated by high field ESR. Owing to the high spectral resolution by high fields and high frequencies, observed ESR signals can be separated into the contributions of the finite chains with various chain length. The chain length dependence of the interaction has been obtained experimentally for the first time, and the correlation length in the real system is discussed. Less

发现了金刚石链、三角链和锯齿链体系的新模型物质，并研究了下列新的场致量子现象：1）首次发现了金刚石链Cu_3（CO_3）_2（OH）_2的模型物质。磁化率结果显示出两个峰值，表明体系中存在两种短程有序。低温磁化强度测量显示了1/3的磁化平台，这是首次在金刚石链模型物质中观察到的。通过对Cu_3（CO_3）_2（OH）_2的磁化曲线的分析，确定了Cu_3（CO_3）_2（OH）_2的交换作用。高场ESR测量显示了系统的动力学过程和在磁化平台处的直接跃迁; 2）在高场下观察到了直到饱和磁化强度的呼吸模、场感生间隙的减小以及高于饱和场的激发模的交叉效应 ...更多信息 e维反铁磁体苯甲酸铜。在一维混晶BaCu_2（Si_格克斯）_2O_7中也观察到了呼吸模<1-x>。3）详细研究了二维二聚体SrCu_2（BO_3）_2中的两三重态束缚态。4）首次在巨磁性分子中观察到了磁化平台，并讨论了系统中的阻挫效应。在4.2K的压力下，用我们新的高场电子自旋共振（ESR）系统直接观察到了二聚体KCuCl_3在10 kbar的压力下的自旋能隙被抑制。6）用高场ESR研究了有限Halfenchain系统的精细能量结构。由于高场和高频率的高光谱分辨率，观察到的ESR信号可以分离成不同链长的有限链的贡献。首次从实验上得到了相互作用对链长的依赖关系，并讨论了真实的体系中的关联长度。少