# Ferromagnetism and spin-valley liquid states in moiré correlated insulators

@article{Wu2019FerromagnetismAS, title={Ferromagnetism and spin-valley liquid states in moir{\'e} correlated insulators}, author={Xiao-chuan Wu and Anna Keselman and Chao-Ming Jian and Kelly Ann Pawlak and Cenke Xu}, journal={Physical Review B}, year={2019} }

Motivated by the recent observation of evidences of ferromagnetism in correlated insulating states in systems with Moir\'{e} superlattices, we study a two-orbital quantum antiferromagnetic model on the triangular lattice, where the two orbitals physically correspond to the two valleys of the original graphene sheet. For simplicity this model has a SU(2)$^s$$\otimes$SU(2)$^v$ symmetry, where the two SU(2) symmetries correspond to the rotation within the spin and valley space respectively… Expand

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#### References

SHOWING 1-10 OF 45 REFERENCES

Origin of Mott insulating behavior and superconductivity in twisted bilayer graphene.

- Physics, Materials Science
- 2018

A remarkable recent experiment has observed Mott insulator and proximate superconductor phases in twisted bilayer graphene when electrons partly fill a nearly flat mini-band that arises a `magic'… Expand

Coupled-wire description of the correlated physics in twisted bilayer graphene

- Physics
- Physical Review B
- 2019

Since the discovery of superconductivity and correlated insulator at fractional electron fillings in the twisted bilayer graphene, most theoretical efforts have been focused on describing this system… Expand

Pseudo Landau level representation of twisted bilayer graphene: Band topology and implications on the correlated insulating phase

- Physics
- Physical Review B
- 2019

We propose that the electronic structure of twisted bilayer graphene (TBG) can be understood as Dirac fermions coupled with opposite pseudomagnetic fields generated by the moir\'e pattern. The two… Expand

Unconventional superconductivity in magic-angle graphene superlattices

- Medicine
- Nature
- 2018

The realization of intrinsic unconventional superconductivity is reported—which cannot be explained by weak electron–phonon interactions—in a two-dimensional superlattice created by stacking two sheets of graphene that are twisted relative to each other by a small angle. Expand

Pressure-induced metal-insulator transition in twisted bilayer graphene

- Physics
- Physical Review B
- 2019

Recent experiments [arXiv: 1808.07865] on twisted bilayer graphene (TBLG) show that under hydrostatic pressure, an insulating state at quarter-filling of the moir\'e superlattice (i.e., one charge… Expand

Evidence of a gate-tunable Mott insulator in a trilayer graphene moiré superlattice

- Physics
- 2018

The Mott insulator is a central concept in strongly correlated physics and manifests when the repulsive Coulomb interaction between electrons dominates over their kinetic energy1,2. Doping additional… Expand

Deconfined quantum critical point on the triangular lattice

- Physics
- 2018

We first propose a topological term that captures the "intertwinement" between the standard "$\sqrt{3} \times \sqrt{3}$" antiferromagnetic order (or the so-called 120$^\circ$ state) and the… Expand

SymmetricZ2spin liquids and their neighboring phases on triangular lattice

- Physics
- 2016

Motivated by recent numerical discovery of a gapped spin liquid phase in spin-$1/2$ triangular-lattice $J_1$-$J_2$ Heisenberg model, we classify symmetric $Z_2$ spin liquids on triangular lattice in… Expand

Chiral Spin Density Wave and d+id Superconductivity in the Magic-Angle-Twisted Bilayer Graphene.

- Physics, Medicine
- Physical review letters
- 2018

It is found that chiral d+id topological superconductivity bordering the correlated insulating state near half-filling, identified as noncoplanar chiral spin-density wave ordered state, featuring the quantum anomalous Hall effect. Expand

Triangular antiferromagnetism on the honeycomb lattice of twisted bilayer graphene

- Physics, Materials Science
- Physical Review B
- 2018

We present the electronic band structures of states with the same symmetry as the three-sublattice planar antiferromagnetic order of the triangular lattice. Such states can also be defined on the… Expand