Driven by quantum geometric effects, nontrivial superfluid weight in flat-band superconductors has recently attracted considerable attention. In this paper, we show that for multigap superconductors, in which each band possesses a distinct gap function, the second-order correction to the gap function is essential for the geometric superfluid weight. Within the mean-field approximation, we derive a formula for the geometric superfluid weight of multigap superconductors that maintains the same form as in the isolated band limit. Beyond the isolated band limit, our formula establishes lower and upper bounds for the geometric superfluid weight. Comparison with recent experimental results on magic-angle twisted bilayer graphene reveals that our predicted upper bound is in good agreement with the experimental data.

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• Quantum geometry
• Superconductors
• Bogoliubov-de Gennes equations