Fig. 5
From: Hallmark features of conventional BCS superconductivity in 2H-TaS2
Crystal structures and schematic electronic band structures of TaS2 polymorphs. (a) Crystal structure (space group \(P6_3/mmc\)) and schematic band structure of the 2H-TaS2 polymorph. The trigonal prismatic coordination results in broad dispersive bands, isotropic electronic properties, and weak electronic correlations, facilitating conventional superconductivity. (b) Crystal structure (space group \(P\bar{3}m1\)) and schematic electronic band structure of the 1T-TaS2 polymorph. The octahedral coordination environment around Ta atoms leads to strong electronic correlations, narrow bands, and a prominent CDW state, driving the system toward a Mott insulating ground state. (c) Crystal structure (space group \(P\bar{3}6/mmc\)) and calculated band structure of the 4Hb-TaS2 polymorph, consisting of alternating layers (1T, 1T′, 1H, 1H′) creating structural asymmetry. The resulting complex structure supports multiband superconductivity, local symmetry breaking, and unconventional pairing mechanisms, including chiral superconductivity with time-reversal symmetry breaking (TRSB). In the structural models, blue spheres represent S atoms, and red spheres represent Ta atoms. The dashed red lines in the band structures indicate the Fermi level \(E_\textrm{F}\).
