Electric Field Induced Superconductivity in Bilayer Octagraphene

TL;DR

This paper explores how applying a perpendicular electric field to bilayer octagraphene can induce a transition from antiferromagnetic order to unconventional superconductivity by altering the electronic band structure and Fermi surface nesting.

Contribution

It demonstrates that electric field tuning can control magnetic and superconducting states in bilayer octagraphene, revealing a new method to induce superconductivity in this material.

Findings

Electric field increases band splitting in bilayer octagraphene.

Fermi surface nesting weakens with increasing electric field.

Superconductivity emerges as SDW order is suppressed by the electric field.

Abstract

We investigate the energy bands, magnetism, and superconductivity of bilayer octagraphene with A-A stacking under a perpendicular electric field. A tight-binding model is used to analyze the band structure of the system. The doubling of the unit cell results in each band of the single layer splitting into two. We find that applying a perpendicular electric field increases the band splitting. As the electric field strength increases, the nesting of the Fermi Surface(FS) weakens, eventually disrupting the antiferromagnetic order and bilayer octagraphene exhibits superconductivity. Spin fluctuations can induce unconventional superconductivity with s+--wave pairing. Applying a perpendicular electric field to bilayer octagraphene parent weakens the nesting of the FS, ultimately killing the spin-density-wave (SDW) ordered state and transitioning it into the superconducting state, whichworks as a doping effect. We use the random-phase approximation approach to obtain the pairing eigenvalues and pairing symmetries of the perpendicular electric field-tuned bilayer octagraphene in the weak coupling limit. By tuning the strength of the perpendicular electric field, the critical interaction strength for SDW order can be modified, which in turn may promote the emergence of unconventional superconductivity.