Superconducting fluctuation effects on the local electronic spin susceptibility

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Abstract
The local electronic spin susceptibility above a superconducting transitions is calculated in a finite-temperature diagrammatic expansion in the order parameter using the Gorkov scheme. While the real part of the susceptibility follows the fluctuations in the order parameter, to lowest order, the imaginary part is found to be enhanced considerably. The leading term originates in the anomalous propagator and describes an energy-conserving scattering of an electron-hole pair into a hole-electron pair by the fluctuation. Higher-order terms diverge even more strongly and yield a convergence criterion similar to that of Ginzburg.