$\mu$SR Investigation of Superconducting PbTaSe$_2$

Noncentrosymmetric superconductors are a topic of considerable interest in the condensed matter physics community. These materials have the potential to exhibit exotic superconducting states, particularly in the presence of strong spin orbit coupling. PbTaSe$_2$ is a noncentrosymmetric material which has very strong spin orbit coupling, and is superconducting with a T$_C$ of 3.6~K. Previous studies of this material have identified exotic properties such as Dirac cones gapped by spin-orbit coupling [1], a topological semi-metal state, and possible multi-band superconductivity [2]. To further explore this material, it is of considerable interest to investigate the pairing symmetry of the superconducting state, and determine whether odd-parity superconductivity may exist. In this talk we will present a $\mu$SR investigation of the penetration depth temperature dependece to infer the pairing symmetry. We will also present zero field $\mu$SR measurements which suggest that this material has an even-parity superconducting state. [1] M.N. Ali et al. Physical Review B 69, 020505(R) (2014) [2] C.-L. Zhang et al. Physical Review B 93, 054520 (2016)