Chiral Criticality In The Doped Helimagnets Mn1-Yfeysi

The critical spin fluctuations in Mn1-yFeySi compounds have been studied by means of ac-susceptibility measurements, polarized neutron small angle scattering, and spin echo spectroscopy. It is shown that these compounds undergo the transition from the paramagnetic to helimagnetic phase through continuous yet well distinguishable crossovers: (i) from paramagnetic to partially chiral and (ii) from partially chiral to highly chiral fluctuating state. The temperature crossovers are associated with the enhancing influence of the Dzyaloshinskii-Moria interaction close to T-c.