The weak itinerant ferromagnet MnSi orders with a left-handed helical spin structure below TC \textonequarter{} 29 K. The helicity with a vector m \textonequarter{} \textonehalf{}S1ÂS2Š=S2 along the crystallographic axis [1 1 1] is realized by an antisymmetric Dzyaloshinski\textendash{}Moriya interaction. The small angle diffraction study with polarized neutrons on a single MnSi crystal was performed within the temperature range from 10 K to TC and the magnetic field B from 1 to 350 mT. The single crystal was oriented in such a way that two axes [1 1 1] and [1 1 À1] were set in a plane perpendicular to the incident beam. Four major diffraction peaks at 7q1 and 7q2 along the axes and four minor peaks at q \textonequarter{} 7q17q2 were observed. The intensity Ip \textonequarter{} I\dh\th{}P0\TH{} \th{} I\dhÀP0\TH; the polarization Pp \textonequarter{} \textonehalf{}I\dh\th{}P0\TH{} À I\dhÀP0\TH{}Š=Ip and the position qp of the peaks were measured as a function of the temperature and the magnetic field. From intensity of the peaks the chiral critical exponent is obtained as b \textonequarter{} 0:4770:04: r 2004 Elsevier B.V. All rights reserved.     «

The weak itinerant ferromagnet MnSi orders with a left-handed helical spin structure below TC \textonequarter{} 29 K. The helicity with a vector m \textonequarter{} \textonehalf{}S1ÂS2Š=S2 along the crystallographic axis [1 1 1] is realized by an antisymmetric Dzyaloshinski\textendash{}Moriya interaction. The small angle diffraction study with polarized neutrons on a single MnSi crystal was performed within the temperature range from 10 K to TC and the magnetic field B from 1 to 350 mT. The sin...     »