Investigating unconventional superconducting ground sate of topological superconductor Nb0.25Bi2Se3

Nb0.25Bi2Se3 is a topological superconductor with a transition temperature of 3.5 K and host zero energy Bogoliubov quasiparticles that mimic Majorana Fermions. In Nb0.25Bi2Se3 rotational symmetry breaking was reported with the existence of nematic order in the superconducting phase. Interestingly, there is also evidence that it breaks time-reversal symmetry (TRS). However, there is no direct evidence. Here, we proposed to study the superconducting properties of Nb0.25Bi2Se3 by a combination of zero-field (ZF)- and transverse-field (TF)-µSR measurements. We plan to investigate the evidence for TRS breaking and an unconventional component of its superconducting order parameter due to the presence of topological surface states.