Magnetic properties and electronic structure of organic crystals.

研究了TTF和BEDT-TTF与MX_4(M=Mn，Co，Cu；X=Cl，Br)形成的络合物以及具有有机自由基取代基的TTF的电荷转移络合物的磁性，以观察传导电子和定域电子之间的磁相互作用。在EPR实验中，观察到了BEDT-TTF-CoCl4、BEDT-TTF-MnCl4和TTF-MnCl4体系的g随温度的移动。在TTF-MnCl4.2体系中也发现了短程磁序的指示。发现对硝基苯基硝基氮氧化物(p-NPNN)的正交相在0.6K时向铁磁有序态转变，这是由轻元素(H、C、N和O)组成的有机化合物中的第一个体铁磁性的例子。测量了交流磁化率、热容、磁滞回线和T_c以下的自发磁化强度，证实了其铁磁性。3.通过对约20个苯基硝基氮氧化物衍生物的磁结构关联研究，得出了铁磁耦合的共同结构特征。4.研究了基态分别为三重态和四重态的硝基氮氧化物双自由基和三自由基磁性，考察了分子内交换作用和分子间交换作用之间的竞争效应。特别是，双自由基表现出非常复杂的磁性行为，伴随着晶体结构随温度和自旋量子效应的变化。

The magnetic properties of TTF and BEDT-TTF complexes with MX_4 (M=Mn, Co, Cu; X=Cl, Br) and charge transfer complexes of TTF having an organic radical substituents were examined to see magnetic interaction between conduction electrons and localized electrons. In EPR experiments, g-shift with temperature has been observed in the BEDT-TTF-CoCl_4, BEDT-TTF-MnCl_4 and TTF-MnCl_4 systems. An indication of short range magnetic order was also found in the system of TTF-MnCl_4.2. The orthorhombic phase of p-nitrophenyl nitronyl nitroxide (p- NPNN) has been found to undergo a transition towards ferromagnetic ordered state at 0.6 K. This is the first example of bulk ferromagnetism in organic compound composed of light elements(H, C, N and O). The ferromagnetism has been comfirmed by the measurements of ac susceptibility, heat capacity, hysteresis curve and spontaneous magnetization below Tc. 3. Thecommon structural feature for ferromagnetic coupling has been deduced from the studies of magneto-structural correlation in about 20 derivatives of phenyl nitronyl nitroxide. 4. The magnetic properties of a biradical and a triradical based on nitronyl nitroxide, the ground spin states of which are triplet and quartet respectively, have also been studied to see the effect of competition between the intramolecular exchange interaction and intermolecular exchange interaction. In particular, the biradical showed very complex magnetic behavior accompanying crystal structure change with temperature and spin quantum effect.