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

发现了金刚石链、三角链和锯齿链体系的新模型物质，并研究了以下新的场致量子现象：1)首次发现了金刚石链Cu3(CO3)2(OH)2的模型物质。磁化率结果显示有两个峰，表明该体系存在两种短程有序结构。低温磁化强度测量显示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。通过对磁化曲线的理论分析，确定了Cu3(CO3)2(OH)2的交换作用。高场ESR测量显示了系统的动力学和在磁化平台上发生变化的直接跃迁。2)在On…中观察到了直到饱和磁化强度的呼吸模式，在强磁场下的场感应隙减小，以及饱和磁场以上激发模的交叉效应。更e维的反铁磁体--苯甲酸铜。在一维混晶体系BaCu2(Si&lt；1-x&gt；Gex)2O7.3中也观察到了呼吸模。详细研究了二维二聚体体系SrCu2(BO_3)_2.4的两三重束结态。首次在巨磁分子中观察到了磁化平台，并讨论了体系中的受挫效应。在4.2K的压力下，我们用我们新的高场ESR系统观察到了KCuCl3体系的直接跃迁，在4.2K的压力下直接观察到了自旋能隙的抑制。6)用高场ESR研究了有限Haldane链系统的精细能量结构。由于高场高频的高光谱分辨率，观测到的ESR信号可以分解成不同链长的有限个链的贡献。首次从实验上得到了相互作用的链长依赖关系，并讨论了实际系统中的关联长度。较少

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