Chiral magnetism in an itinerant helical magnet, MnSi; An Extended Si NMR study

Yasuoka, Hiroshi; Motoya, Kiyoichiro*; Majumder, M.*; Witt, S.*; Kerllner, C.*; Baenitz, M.*

The microscopic magnetism in the helical, the conical and the ferromagnetically polarized phases in an itinerant helical magnet, MnSi, has been studied by an ex-tended Si NMR at zero field and under external magnetic fields. The temperature dependence of staggered moment, ), determined by the Si NMR frequency, , and nuclear relaxation rate, 1/ () is in general accord with the SCR theory for weak itinerant ferromagnetic metals and its extension. The external field dependence of resonance frequency, ), follows a vector sum of the contributions from atomic hyperfine and macroscopic fields with a field induced moment characteristic to the itinerant magnets. A discontinuous jump of the resonance frequency at the critical field, , between the conical and the polarized phases has also been found that suggests a first order like change of the electronic states at .