Fig. 2: Temperature dependence of the superconducting susceptibility for a large phonon frequency Ω = 4.0t. | Communications Physics

Fig. 2: Temperature dependence of the superconducting susceptibility for a large phonon frequency Ω = 4.0t.

From: Relative importance of nonlinear electron-phonon coupling and vertex corrections in the Holstein model

Fig. 2

Results are shown for a filling of n = 0.55 and a lattice size N = 10 × 10. Both the linear (ξ = 0, blue squares) and nonlinear (ξ = 0.05, green triangles) Holstein model results from determinant quantum Monte Carlo (DQMC) show a rapid growth of pairing correlations with decreasing temperature, but approach different asymptotes. The self-consistent Migdal approximation (SCMA) results (red dashed line), shown here for reference, yield a large and inaccurate estimate for the superconducting critical temperature due to the invalidity of Migdal’s approximation. The lines connecting DQMC data are spline-interpolated and used only to guide the eye. Error bars on the DQMC data points are one standard deviation statistical errors estimated using jackknife resampling.

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