Metal-insulator transition of donor-acceptor-type organic charge-transfer complex (BETS)2(Br2TCNQ): Site-selective NMR measurements
Metal-insulator transition of donor-acceptor-type organic charge-transfer complex (BETS)2(Br2TCNQ): Site-selective NMR measurements
复制标题
供体-受体型有机电荷转移络合物 (BETS)2(Br2TCNQ) 的金属-绝缘体转变：位点选择性 NMR 测量
DOI：
10.1103/physrevb.66.035104
复制
发表时间：
2002
影响因子：
3.7
通讯作者：
Y. Iwasa
中科院分区：
文献类型：
--
作者：
K. Hiraki;S. Furuta;Toshihiro Takahashi;R. Kondo;S. Kagoshima;T. Hasegawa;T. Mochida;Y. Iwasa
通过位点选择性核磁共振测量研究了供体层和受体堆栈在电荷转移复合物$(\mathrm{BETS}{)}_{2}({\mathrm{Br}}_{2}\mathrm{TCNQ})$的电子特性中的作用。 ${}^{77}\mathrm{Se}$ NMR 的线展宽表明在金属-绝缘体转变温度 12 K 处观察到 BETS 位点上的磁有序。这种转变是由 BETS 层上的自旋密度波形成引起的。 ${}^{13}\mathrm{C}$ 对 ${\mathrm{Br}}_{2}\mathrm{TCNQ}$ 分子中氰基碳的 NMR 证实，自旋单线态在 170 K 以下的一维 ${\mathrm{Br}}_{2}\mathrm{TCNQ}$ 列上开始形成，其三维排序出现在 80 K 以下。 NMR 线形状和位移，磁化率分解为 BETS 和 ${\mathrm{Br}}_{2}\mathrm{TCNQ}$ 位点的贡献。
The roles of donor layers and acceptor stacks in the electronic properties of the charge transfer complex, $(\mathrm{BETS}{)}_{2}({\mathrm{Br}}_{2}\mathrm{TCNQ})$ were investigated by means of site-selective NMR measurements. Line broadening of ${}^{77}\mathrm{Se}$ NMR indicating a magnetic ordering on the BETS site was observed at the metal-insulator transition temperature 12 K. This transition is caused by the spin-density-wave formation on the BETS layers. ${}^{13}\mathrm{C}$ NMR on the cyano carbon in the ${\mathrm{Br}}_{2}\mathrm{TCNQ}$ molecule confirms that a spin singlet formation starts to develop on the one dimensional ${\mathrm{Br}}_{2}\mathrm{TCNQ}$ columns below 170 K and its three dimensional ordering appears below 80 K. From the analysis of the NMR line shape and shift, magnetic susceptibility was decomposed into the contributions of the BETS and ${\mathrm{Br}}_{2}\mathrm{TCNQ}$ sites.