摘要
受垂直电场可调控Ruddlesden–Popper双层镍酸盐La3Ni2O7超导性质的启发，本研究采用动力学簇量子蒙特卡洛方法求解不平衡双轨道双层Hubbard模型。通过分析未掺杂、空穴掺杂及电子掺杂情形下电场诱导的配对对称性及其演化，发现源自dz2轨道的s±波配对被抑制，同时层间dz2轨道失配及电子向dx2-y2轨道转移驱动了从s±波到d波的配对对称性转变。有趣的是，由dx2-y2轨道产生的d波配对随电场强度呈现穹顶状行为。大规模多体计算与弱耦合方法的预期一致，为理解RP镍酸盐的超导机制提供了新见解。
材料
方法
- dynamical cluster approximation (DCA)
- continuous-time auxiliary-field quantum Monte Carlo (CT-AUX QMC)
- Bethe-Salpeter equation
关键词
- pairing symmetry transition
- dome shaped behavior
- electric field
- orbital mismatch
亮点
- The d-wave pairing exhibits a dome-shaped behavior as a function of electric field strength.
- The large-scale many-body calculations are consistent with weak-coupling predictions.
结论
- The s±-wave pairing from the d_z2 orbital is suppressed by the electric field, while d-wave pairing from the dx2-y2 orbital emerges with a dome-like behavior.
- The transition from s±-wave to d-wave occurs due to interlayer orbital mismatch and electron transfer to the dx2-y2 orbital.
主要论断
- Applying a perpendicular electric field to bilayer La3Ni2O7 suppresses s±-wave pairing from dz2 orbital and induces d-wave pairing from dx2-y2 orbital
- 证据: DCA calculations show that eigenvalues for s± pairing decrease with increasing V, while d-wave eigenvalues exhibit dome-like behavior, with maximum d-wave Tc exceeding s± Tc at intermediate V
研究流程
- Model construction — s±-wave pairing suppressed, d-wave pairing emerges with electric field
- 材料: Two-orbital bilayer Hubbard model
- 方法: Dynamical cluster approximation (DCA) with CT-AUX solver
- 观察: BSE eigenvalues for s± and d-wave channels
- Data analysis — Pairing symmetry transition from s± to d-wave
- 方法: Extrapolation of Tc from eigenvalues; Orbital-resolved pair-field susceptibility
- 观察: Dome-like behavior of d-wave Tc with electric field