TF-μSR Sensitivity to Charge Density Wave Order in 2H-NbSe2

The sensitivity of transverse-field muon spin rotation (TF-μSR) to static charge-density wave (CDW) order in the bulk of 2H-NbSe2 is demonstrated. In the presence of CDW order, the quadrupolar interaction of the 93Nb nuclei with the local electric-field gradient is modified, and this in turn affects the magnetic dipolar coupling of the positive muon to these nuclei. For a weak magnetic field applied parallel to the c-axis, we observe a small enhancement of the muon depolarization rate at temperatures below the established CDW phase transition. Aligning the applied field perpendicular to the c-axis, we observe a sensitivity to static CDW order in regions of the sample extending up to a temperature nearly 3 times the CDW transition temperature T CDW. The results suggest that the muon is mobile over the temperature range explored above the superconducting transition temperature Tc, but becomes trapped in the vicinity of defects.