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arXiv 2009.06644cond-mat.str-elcond-mat.stat-mechcond-mat.supr-conhep-lathep-th
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竞争节结d波超导性和反铁磁性

Competing nodal d-wave superconductivity and antiferromagnetism

Xiao Yan Xu, Tarun Grover

摘要:

几种强关联量子材料中广泛存在着相互竞争的非常规超导性和反铁磁性,但直接模拟往往存在费米子符号问题。在这里,我们报告无偏量子蒙特卡罗(QMC)模拟的符号问题,免费的排斥玩具模型与相同的现场对称性的标准哈伯德模型的二维正方形格子。使用QMC,补充平均场和连续场理论的参数,我们发现,它主机三个不同的阶段:一个节点的d波阶段,反铁磁体,和一个干预阶段,主机共存的反铁磁性和无节点的d波超导。从共存相到反铁磁相的转变用2+1-D XY普适类描述,而从共存相到节d波相的转变用Heisenberg-Gross-Neveu理论描述。我们的相图的拓扑结构类似于层状有机材料,其在半填充时具有从反铁磁体到非常规超导体的压力调谐Mott转变。

英文摘要:

Competing unconventional superconductivity and antiferromagnetism widely exist in several strongly correlated quantum materials whose direct simulation generally suffers from fermion sign problem. Here we report unbiased Quantum Monte Carlo (QMC) simulations on a sign-problem-free repulsive toy model with same onsite symmetries as the standard Hubbard model on a 2D square lattice. Using QMC, supplemented with mean-field and continuum field-theory arguments, we find that it hosts three distinct phases: a nodal d-wave phase, an antiferromagnet, and an intervening phase which hosts coexisting antiferromagnetism and nodeless d-wave superconductivity. The transition from the coexisting phase to the antiferromagnet is described by the 2+1-D XY universality class, while the one from the coexisting phase to the nodal d-wave phase is described by the Heisenberg-Gross-Neveu theory. The topology of our phase diagram resembles that of layered organic materials which host pressure tuned Mott transition from antiferromagnet to unconventional superconductor at half-filling.

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