Multiple ground states of the transition-metal dichalcogenide TaS2

Low dimensional materials have been a major subject of interest in recent years. In particular, the transitions metal dichalcogenides (TMDs), a quasi-2D layered materials with weak van der Waals coupling between the layers, received a lot of attention. TMDs exhibit strong electron-electron and electron-phonon interactions that lead to complicated phase diagrams showing a variety of ground states. 

In this work we explore the multiple ground state of the highly polymorphic TMD TaS2. We have characterized its physical properties using angle-resolved photoemission spectroscopy (ARPES), muon-spin relaxation (muSR) and electrical transport measurements. In this talk I will describe the crystal structure and its physical properties. I will show that the common understanding of the insulating ground state of 1T-TaS2 as a realization of Mott insulator on a triangular lattice might be wrong. Next, I will describe a method for driving the crystal from an insulator to superconductor (SC). The properties of this SC were thoroughly investigated in variety of methods. Remarkably, it was found to break time-reversal symmetry (TRS) which suggest an unconventional, chiral SC.