Bond-order and charge-density waves in the isotropic interacting two-dimensional quarter-filled band and the insulating state proximate to organic superconductivity
Bond-order and charge-density waves in the isotropic interacting two-dimensional quarter-filled band and the insulating state proximate to organic superconductivity
复制标题
各向同性相互作用的二维四分之一填充带和接近有机超导的绝缘态中的键序和电荷密度波
DOI：
10.1103/physrevb.62.13400
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发表时间：
2000
影响因子：
3.7
通讯作者：
D. Campbell
中科院分区：
文献类型：
--
作者：
S. Mazumdar;R. T. Clay;D. Campbell
我们报告了三个令人惊讶的结果，关于在二维（2D），四分之一填充带的空间破碎对称性的性质与强电子-电子相互作用，提供了一个微观模型的2：1阳离子有机电荷转移固体（CTS的）。首先，在直接矛盾的单电子理论的预测，我们发现一个共存的“键序和电荷密度波”（BCDW）绝缘基态的所有各向异性，包括各向同性的限制在二维矩形晶格。第二，与当链间耦合从零增加时表现出一个单线态到反铁磁体（AFM）转变的相互作用半填充带相反，在相互作用四分之一填充带中发生两个不同的转变：类似的单线态到反铁磁体/自旋密度波（AFM/SDW）跃迁在小的链间耦合，产生键-电荷-自旋密度波（BCSDW）状态，接着是在大链间耦合下的第二次AFM/SDW到单重态转变。第三，我们表明，我们的结论保持不变，如果一个假设传统的"有效的1/2填充“晶格的二聚体网站的CTS的：二聚体晶格无条件地再次二聚，给相同的BCDW中发现的四分之一填充带。我们在四甲基四硫富瓦烯（TMTTF），四甲基四硒富瓦烯（TMTSF），双乙撑二硫代四硫富瓦烯（BEDT-TTF）和双乙撑二硫代四硒富瓦烯（BETS）为基础的CTS的最近的实验进行了详细的比较。我们的理论解释了在TMTSF和某些BEDT-TTF系统中观察到的混合电荷-自旋密度波，以及在基于BETS的系统中没有反铁磁性。这项工作的一个重要结果是建议，有机超导性与近库仑诱导的BCDW，与SDW共存的大各向异性也是BCDW的结果，而不是超导电性的驱动程序。我们指出，BCDW和BCSDW状态类似于四种不同类别的“成对”半导体，这些半导体是在某些模型中获得的。所有这四种模型原则上都可以在弱不相称区域中产生超导性，这为BCDW可能驱动有机物中的超导性的概念提供了进一步的动力。
We report three surprising results regarding the nature of the spatial broken symmetries in the two-dimensional (2D), quarter-filled band with strong electron-electron interactions that provides a microscopic model of the 2:1 cationic organic charge-transfer solids (CTS's). First, in direct contradiction to the predictions of one-electron theory, we find a coexisting ``bond-order and charge-density wave'' (BCDW) insulating ground state in the 2D rectangular lattice for all anisotropies, including the isotropic limit. Second, in contrast to the interacting half-filled band, which exhibits one singlet-to-antiferromagnet (AFM) transition as the interchain coupling is increased from zero, there occur in the interacting quarter-filled band two distinct transitions: a similar singlet-to-antiferromagnet/spin-density wave (AFM/SDW) transition at small interchain coupling, giving rise to a bond-charge-spin density wave (BCSDW) state, followed by a second AFM/SDW-to-singlet transition at large interchain coupling. Third, we show that our conclusions remain unchanged if one assumes the conventional ``effective 1/2-filled'' lattice of dimer sites for the CTS's: the dimer lattice unconditionally dimerizes again to give the same BCDW found in the quarter-filled band. We make detailed comparisons to recent experiments in the tetramethyl-tetrathiafulvalene (TMTTF), tetramethyl-tetraselenafulvalene (TMTSF), bisethylenedithio-tetrathiafulvalene (BEDT-TTF) and bisethylenedithio-tetraselenafulvalene (BETS)-based CTS's. Our theory explains the mixed charge-spin density waves observed in TMTSF and certain BEDT-TTF systems, as well as the absence of antiferromagnetism in the BETS-based systems. An important consequence of this work is the suggestion that organic superconductivity is related to the proximate Coulomb-induced BCDW, with the SDW that coexists for large anisotropies being also a consequence of the BCDW, rather than the driver of superconductivity. We point out that the BCDW and BCSDW states are analogous to four different classes of ``paired'' semiconductors that are obtained within certain models of exotic superconductivity. That all four of these models can in principle give rise to superconductivity in the weakly incommensurate regime provides further motivation for the notion that the BCDW may be driving the superconductivity in the organics.