Magnetization amplification in the interlayer pairing superconductor 4Hb-TaS2

A recent experiment on the bulk compound 4Hb-TaS2 reveals an unusual time-reversal symmetry-breaking superconducting state that possesses a magnetic memory not manifest in the normal state. Here we provide one mechanism for this observation by studying the magnetic and electronic properties of 4Hb-TaS2. We discuss the criterion for a small magnetization in the normal state in terms of spin and orbital magnetization. Based on an analysis of lattice symmetry and Fermi surface structure, we propose that 4Hb-TaS2 realizes superconductivity in the interlayer, equal-spin channel with a gap function whose phase winds along the Fermi surface by an integer multiple of 6π. The enhancement of the magnetization in the superconducting state compared to the normal state can be explained if the state with a gap winding of 6π is realized, accounting for the observed magnetic memory. We discuss how this superconducting state can be probed experimentally by spin-polarized scanning tunneling microscopy.