Chiral charge density wave in 1T- and 4Hb-TaS2: the role of interlayer coupling

We use micro-angle-resolved photoemission spectroscopy (micro-ARPES) to investigate chiral charge density waves (CDWs) in 4Hb-TaS2 with micron-scale spatial resolution. In the 1T layers of 4Hb-TaS2, we uncover coexisting left- and right-handed CDW domains and resolve four distinct spectral patterns arising from the interplay of chirality and rotational stacking. In contrast, bulk 1T-TaS2 exhibits uniform chirality. In addition, 4Hb-TaS2 shows negligible out-of-plane dispersion of the 1T-derived bands, in contrast to the large interlayer coupling observed in bulk 1T-TaS2. Density Functional Theory (DFT) calculations corroborate this picture, revealing that the interlayer interaction of the chiral order in 4Hb-TaS2 is nearly two orders of magnitude weaker than in the 1T polytype. Our findings establish 4Hb-TaS2 as a quasi-two-dimensional platform for exploring tunable chiral CDW phenomena.