Interior-gap superconductivity has long been discussed as an exotic paired state in the presence of Fermi-surface mismatch, but its realization in canonical strongly correlated models has remained elusive. Here we present evidence that the superconducting phase of one-dimensional Kondo-Heisenberg models realizes an interior-gap pair density wave (PDW) state generated by strong correlations. Combining infinite density-matrix-renormalization-group (iDMRG) and finite DMRG calculations for $S=1/2$ and $S=3/2$ chains, we show that the PDW correlation is the dominant bulk superconducting correlation in the spin-gapped regime and that the momentum distribution function $n\left(k\right)$ exhibits a reconstructed structure characteristic of interior-gap physics. In particular, while the feature in $n\left(k\right)$ for the $S=1/2$ chain is only humplike, the corresponding structure in the $S=3/2$ chain develops into a clear dip, strongly supporting the interpretation in terms of an interior-gap-like dip structure. Unlike conventional interior-gap scenarios based on a mismatch between preexisting Fermi surfaces, the present system starts from a single bare conduction-electron Fermi surface, and the additional low-energy single-particle structure emerges dynamically together with the dominant PDW correlation through the Kondo coupling. Finite DMRG data further demonstrate that boundary effects can substantially modify real-space correlations in this gapless one-dimensional system, making a direct thermodynamic-limit calculation essential for identifying the intrinsic bulk momentum structure and the dominant correlation channel.

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• Luttinger's theorem
• Pair density wave
• Superconductivity
• Heavy-fermion systems
• Density matrix renormalization group
• Kondo lattice model