Experimental evidence of spontaneous time-reversal (TR) symmetry breaking have been reported for the superconducting ground state in the transition metal dichalcogenide (TMD) superconductor $4{\mathrm{H}}_b\text{−}{\mathrm{TaS}}_2$ or chiral molecule intercalated ${\mathrm{TaS}}_2$ hybrid superlattices, and is regarded as evidence of the emergent chiral superconductivity. However, the $T_c$ of these TMD superconductors is at the same order as pristine 1H or 2H-${\mathrm{TaS}}_2$ that does not show any signature of TR breaking and is believed to be conventional Bardeen-Cooper-Schrieffer superconductors. To resolve this puzzle, we proposed a type of pair-mixing states that mix the dominant conventional s-wave pairing channel with the subdominant chiral p-wave pairing channel via the finite Cooper pair momentum based on the symmetry analysis of the Ginzburg-Landau theory. Our analysis shows the fourth-order terms in the chiral p-wave channel can lead to a variety of pair-mixing states with spontaneous TR breaking. These TR-breaking superconducting states also reveal zero-field junction-free superconducting diode effect that is observed in chiral molecule intercalated ${\mathrm{TaS}}_2$ superlattices.

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• Pair density wave
• Ferromagnetic superconductors
• Unconventional superconductors
• Landau-Ginzburg theory