Disorder as a Superconductivity Enabler: Mott-State Fragility Drives Bulk SC in 4Hb-TaS₂
In 4Hb-TaS₂, a natural heterostructure of interleaved Mott-like (1T) and metallic layers, bulk superconductivity is not an intrinsic clean-limit property but is instead triggered by quenched disorder via Se/S substitution. Disorder delocalizes carriers in the Mott-like layer, nucleating a new Fermi surface absent in pristine samples and unleashing strongly correlated electrons. This reframes the superconducting mechanism: the Mott state's fragility — not conventional pairing symmetry — is the primary enabler, with disorder acting as the tuning parameter rather than a perturbation.