Magnetism and superconductivity in doped triangular-lattice Mott insulators

Abstract

Inspired by recent advances in the fabrication of surface superlattices, and in particular the triangular lattice made of tin (Sn) atoms on silicon, we study an extended Hubbard mode on a triangular lattice. The observations of magnetism in these systems justify the inclusion of a strong on-site repulsion and the observation of superconductivity suggests including an effective, nearest-neighbor attractive interaction. The attractive interaction mimics the effect of strong on-site repulsion near half filling, which can be seen in strong coupling vertex calculations such as the Eliashberg method. With this extended Hubbard model on a triangular lattice with its geometrical frustration, we find a rich phase diagram of various magnetic orders and pairing functions, within the framework of self-consistent mean field theory. We uncover the competition among magnetism and unconventional superconductivity, and their coexistence for triplet pairings. We follow the Fermi surface of the system as the system is doped away from half filling and find nesting vectors and a Lifshitz transition which provide an intuitive understanding of the phase transitions between the many orders we consider.

arXiv comment10 pages, 4 figures;

References in corpus (15)

• Phase diagram of the two-dimensional extended Hubbard model: Phase transitions between different pairing symmetries when charge and spin fluctuations coexist
• Triangular Mott-Hubbard Insulator Phases of Sn/Si(111) and Sn/Ge(111) Surfaces
• Stable topological phases in a family of two-dimensional fermion models
• Topological superconductivity in the doped chiral spin liquid on the triangular lattice
• Evidence for chiral superconductivity on a silicon surface
• Realization of a hole-doped Mott insulator on a triangular silicon lattice
• Superconductivity in a hole-doped Mott-insulating triangular adatom layer on a silicon surface
• Triplet Superconductivity from Nonlocal Coulomb Repulsion in an Atomic Sn Layer Deposited onto a Si(111) Substrate
• Phase diagram of the triangular extended Hubbard model
• Competition between charge and spin order in the $t-U-V$ extended Hubbard model on the triangular lattice
• Unconventional superconductivity in the extended Hubbard model: Weak-coupling renormalization group
• Zero-bias anomaly in nano-scale hole-doped Mott insulators on a triangular silicon surface
• Magnetic excitations, phase diagram and order-by-disorder in the extended triangular-lattice Hubbard model
• Origin of the T${}_c$ enhancement in heterostructure cuprate superconductors
• Causal versus local $GW$+EDMFT scheme and application to the triangular-lattice extended Hubbard model

Cited by in corpus (2)

• Particle-Hole Asymmetry and Pinball Liquid in a Triangular-Lattice Extended Hubbard Model within Mean-Field Approximation
• The electronic structure of a doped Mott-Hubbard surface