Multi-orbital superconductivity in 4Hb-TaS2 in the dirty limit: Part II

<div style="direction: ltr;">The transition metal dichalcogenide 4Hb-TaS₂ consists of alternating single layers of octahedrally oriented T structure and trigonally oriented H structure. Separately, in their bulk form, these two structures have very different ground states: while 1T-TaS₂ is a strongly correlated insulator and a spin-liquid candidate, 2H-TaS₂ is a superconductor. The 4Hb compound also has a superconducting ground state, which has been argued to be chiral due to the onset of a μSR signal concomitant to the superconducting transition. </div> <div style="direction: ltr;">At the same time however, measurements of the heat capacity below Tc indicate the existence of a large density of gapless states. In part II of this talk, we show how a residual Fermi surface can naturally emerge in a multi-pocket superconductor due to pair-breaking impurities with pocket-dependent scattering rates. Based on the DFT calculations and effective tight-binding model introduced in part I, we show how a strong pocket-dependent coupling to magnetic moments arising from the 1T layers naturally forms in this system. We then compute the tunneling DOS and heat capacity, which agree well with the data. </div>