Tantalum Disulfide (4Hb phase, 4Hb-TaS₂)

4Hb-TaS₂ is a distinctive polytype of TaS₂, which can be regarded as a natural heterostructure formed by alternately stacking 1T- and 1H-phase layers, with space group P6₃/mmc. The 1T layers host a charge density wave (CDW) and are considered a candidate quantum spin liquid, while the 1H layers provide superconductivity (Tc ≈ 2.7 K). The alternating coupling of these two electronic states within a single crystal causes 4Hb-TaS₂ to exhibit signatures of unconventional superconductivity—including spontaneous time-reversal symmetry breaking and possible topological superconducting behavior—making it an important platform for studying correlated electrons and unconventional pairing.