  We have investigated the low-temperature local magnetic properties in the
bulk of molten salt-flux (MSF) grown single crystals of the candidate
odd-parity superconductor UTe2 by zero-field muon spin relaxation (muSR). In
contrast to previous muSR studies of UTe2 single crystals grown by a chemical
vapour transport (CVT) method, we find no evidence of magnetic clusters or
electronic moments fluctuating slow enough to cause a discernible relaxation of
the zero-field muSR asymmetry spectrum. Consequently, our measurements on
MSF-grown single crystals rule out the generation of spontaneous magnetic
fields in the bulk that would occur near impurities or lattice defects if the
superconducting state of UTe2 breaks time-reversal symmetry. This result
suggests UTe2 is characterized by a single-component superconducting order
parameter.
