  We propose an alternate scenario for the relation between ferromagnetism (FM)
and superconductivity (SC) in UCoGe at ambient pressure. On the basis of
neutron polarimetry measurement performed in strictly zero field on a
single-crystal at ambient pressure, we claim that the SC phase does exist in
spite of lack of long-range FM order. Moreover, the SC regime dominates to the
paramagnetic (PM) state in small external magnetic fields. Above the critical
SC temperature, TSC = 0.64 K, the zero-field state is characterized by a regime
with strong FM spin fluctuations, suggesting the proximity of the FM quantum
critical point. We present an ambient-pressure phase diagram of UCoGe based on
our resistivity, magnetization and neutron polarimetry results.
