Mott transition and magnetism on the anisotropic triangular lattice
Mott transition and magnetism on the anisotropic triangular lattice
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各向异性三角晶格的莫特跃迁和磁性
DOI：
10.1103/physrevb.94.245133
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发表时间：
2016
影响因子：
3.7
通讯作者：
A. Tremblay
中科院分区：
文献类型：
--
作者：
S. Acheche;A. Reymbaut;M. Charlebois;D. S'en'echal;A. Tremblay
自旋-液体行为最近在实验上被认为是中等一维有机化合物$\kappa$-H$3$(Cat-EDT-TTF)$2$。这种化合物可以用各向异性三角晶格上的单带Hubbard模型来模拟，其中$t‘是少数跃迁。因此，重要的是扩展以前在$0\leq t‘/t\leq 1.2$范围内进行的研究，以找出是否存在在没有长程磁序的情况下可以发现Mott绝缘行为的区域。为此，我们用团簇动力学平均场理论(CDMFT)研究了上述模型在$1.2\leq t‘/t\leq 2$范围内的性质。我们认为重要的是选择一个对称保持的原子簇，而不是准一维原子簇。我们发现，当t‘/t’超过$t^\Prime/t\约1.3$时，零温下的Mott转变被分离金属态和共线磁绝缘态的一级转变所取代。然而，在物理上相关的值$t^\Prime/t\simeq 1.5$时，向磁性相和Mott绝缘相的转变非常接近。本研究得到的相图可以为各向异性三角晶格上的适度一维化合物提供工作基础。
Spin-liquid behavior was recently suggested experimentally in the moderately one-dimensional organic compound $\kappa$-H$_3$(Cat-EDT-TTF)$_2$. This compound can be modeled by the one-band Hubbard model on the anisotropic triangular lattice with $t^\prime/t \simeq 1.5$, where $t'$ is the minority hopping. It thus becomes important to extend previous studies, that were performed in the range $0 \leq t'/t \leq 1.2$, to find out whether there is a regime where Mott insulating behavior can be found without long-range magnetic order. To this end, we study the above model in the range $1.2 \leq t'/t \leq 2$ using cluster dynamical mean-field theory (CDMFT). We argue that it is important to choose a symmetry-preserving cluster rather than a quasi one-dimensional cluster. We find that, upon increasing $t'/t$ beyond $t^\prime/t \approx 1.3$, the Mott transition at zero-temperature is replaced by a first-order transition separating a metallic state from a collinear magnetic insulating state. Nevertheless, at the physically relevant value $t^\prime/t \simeq 1.5$, the transitions toward the magnetic and the Mott insulating phases are very close. The phase diagram obtained in this study can provide a working basis for moderately one-dimensional compounds on the anisotropic triangular lattice.