Origin of the large magnetoresistance in the candidate chiral superconductor 4Hb-TaS2

The intriguing electronic phase diagram involving charge density wave (CDW) transitions in the TaS2 system has been widely investigated over the past decade, especially for the 1T and 2H phases. 4H(b)-TaS2, regarded as the natural heterostructure that combines the characteristics of 1T and 2H-TaS2, has also been the focus recently, due to the prospects for fundamental research and device applications. Here, we have systematically investigated the electrical transport properties of 4H(b)-TaS2 single crystals combined with the band structure calculations and found that the low-temperature phase of candidate chiral superconductor 4H(b)-TaS2 (T-c similar to 3.5 K) at normal state is not the simple CDW but exhibits a strong magnetic field dependence. The most significant result is the emergence of the large magnetoresistance (MR), which may originate from the high mobility of holes and partial compensation. In addition, the symmetry of MR under the low magnetic field has also changed significantly in 4H(b)-TaS2, which is closely related to the CDW structures formed in the H layers at 22 K. The results are conducive to the understanding of the mechanism of MR appearing in layered CDW compounds, and the presence of MR in 4H(b)-TaS2 suggests the potential applications for functional devices in the future.