  The magnetic phase diagram of CuCrO2 was studied with a novel method of
simultaneous Cu NMR and electric polarization techniques with the primary goal
of demonstrating that regardless of cooling history of the sample the magnetic
phase with specific helmet-shaped NMR spectra associated with interplanar
disorder possesses electric polarization. Our result unequivocally confirms the
assumption of Sakhratov et al. Phys. Rev. B \bf{94}, 094410 (2016) that the
high-field low-temperature phase is in fact a 3D-polar phase characterised by a
3D magnetic order with tensor order parameter. In comparison with the results
obtained in pulsed fields, a modified phase diagram is introduced defining the
upper boundary of the first-order transition from the 3D-spiral to the 3D-polar
phase.
