Study of the π-d system involving phthalocyanine conductors

有机稀磁合金Co_<0.01>Ni_<0.99>Pc(AsF_6)_<0.5>涉及Co位的局域自旋和沿一维Pc链的流动π电子。从ESR性能的角度依赖性来看，我们发现CoPc在该合金中被相关取代。基于对各向异性超精细结构的分析，我们确定了原子轨道为3d_<Z^2>，其中有一个未配对电子占据。通过分析g值和线宽对温度的依赖关系，我们成功地确定了Co上的局域自旋和Pc链上的流动电子之间的π-d交换能为|J_<πd>|=0.013 eV。通过分析g值的温度依赖性，确定费米能级的态密度为D_F=3.5 eV^<-1> / a。利用这些参数，我们估计近藤温度为T_K=2×10^<-5> k，交换能的小值来自于特征电子结构和分子排列。在CoPc分子中，HOMO和3d_<Z^2>轨道相互独立分布，导致分子内交换能较小。酞菁分子以金属与金属重叠的方式堆叠。这种重叠使得相邻分子的HOMO与3d_<Z^2>之间的重叠积分可以忽略不计，从而导致分子间交换能很小。根据波段计算，θ-(BDT-TTP)_2Cu(NCS)_2是准二维导体。该化合物在250k左右的电阻率下表现出二级相变。在相变温度以下，我们发现光导谱发生了剧烈的变化，其中最低的电子跃迁到高能侧，打开了一个很大的间隙。极化拉曼光谱的温度依赖性和激发光依赖性表明，在相变温度以下发生了2B^<+0.5>→B^0+B^<+1>的电荷歧化。磁化率和ESR实验表明，分离的电荷沿分子堆栈垂直有序。少

Organic dilute magnetic alloy Co_<0.01>Ni_<0.99>Pc(AsF_6)_<0.5> involves localized spins on Co sites and itinerant π electrons along the one-dimensional Pc chain. From the angular dependence of the ESR properties, we identified that CoPc is relevantly substituted in this alloy. Based on the analysis of the anisotropic hyperfine structure, we determined the atomic orbital as 3d_<Z^2>, in which an unpaired electron is occupied. Analyzing the temperature dependence of g value and linewidth, we succeed to determine the π-d exchange energy between the localized spin on Co and itinerant electrons on Pc chain as |J_<πd>|=0.013 eV.The density of state at the Fermi level is determined as D_F=3.5 eV^<-1> per a spin through the analysis of the temperature dependence of the g value. Using these parameters, we estimate the Kondo temperature as T_K=2×10^<-5> K.The small value of the exchange energy comes from the characteristic electronic structure and molecular arrangement. HOMO and 3d_<Z^2> orbita … More l are separately distributed from each other in the CoPc molecule, which causes the small intra-molecular exchange energy. The phthalocyanine molecules are stacked in a fashion of metal-over-metal overlap. This overlap makes the overlap integral between HOMO and 3d_<Z^2> of adjacent molecule negligibly small, and thus causes the small inter-molecular exchange energy.θ-(BDT-TTP)_2Cu(NCS)_2 is regarded as a quasi-two-dimensional conductor according to the band calculation. This compound shows a second-order phase transition in resistivity around 250 K.Below the phase transition temperature, we found a drastic change in optical conductivity spectrum, in which the lowest electronic transition shifted to high-energy side opening a wide gap. The temperature and excitation light dependence of polaized Raman spectrum indicated that a charge disproportionation such as 2B^<+0.5>→B^0+B^<+1> occurred below the phase transition temperature. The magnetic susceptibility and ESR experiment suggest that the separated charge is vertically ordered along the molecular stack. Less