Variational Monte Carlo Studies of Pairing Symmetry for the t-J Model on a Triangular Lattice
Variational Monte Carlo Studies of Pairing Symmetry for the t-J Model on a Triangular Lattice
复制标题
DOI：
10.1143/jpsj.73.3404
复制
发表时间：
2004-08
影响因子：
1.7
通讯作者：
Tsutomu Watanabe;H. Yokoyama;Yukio Tanaka;J. Inoue;M. Ogata
中科院分区：
文献类型：
--
作者：
Tsutomu Watanabe;H. Yokoyama;Yukio Tanaka;J. Inoue;M. Ogata
作为一种新的超导体NaxCoO 2 ·yH 2 O的模型，用变分Monte Carlo方法研究了三角晶格上的单带t-J模型.我们计算了各种超导态的能量，对于小的J /|不|. s、d和d + id（p + ip和f）波的对称性被用作单重（三重）配对的候选者。此外，长冈铁磁性和相分离的可能性被认为是。结果表明，在SC态中，d + id波总是具有最低的能量，这一结果支持了以前的平均场研究。虽然在特殊情况下（δ=0.5和t <0）f波态相对于正常态变得稳定，但不可能有三重态配对。当t <0时，在δ和J /范围内，完全铁磁态占主导地位|不|，它涵盖了超导电性的实际参数范围。
As a model of a novel superconductor Na x CoO 2 · y H 2 O, a single-band t – J model on a triangular lattice is studied, using a variational Monte Carlo method. We calculate the energies of various superconducting (SC) states, changing the doping rate δ and sign of t for small J /| t |. Symmetries of s , d , and d + id ( p + ip and f ) waves are taken up as candidates for singlet (triplet) pairing. In addition, the possibility of Nagaoka ferromagnetism and phase separation is considered. It is revealed that, among the SC states, the d + id wave always has the lowest energy, which result supports previous mean-field studies. There is no possibility of triplet pairing, although the f -wave state becomes stable relative to a normal state in a special case (δ=0.5 and t <0). For t <0, the complete ferromagnetic state is dominant in a wide range of δ and J /| t |, which covers the realistic parameter region of superconductivity.