NMR and Susceptibility Studies of MnSi aboveTc

The itinerant helimagnet MnSi has been studied using NMR and susceptibility techniques above T c . The magnitude and temperature dependence of the 55 Mn Knight shift K, quadrupole coupling ν Q and the nuclear spin-lattice and spin-spin relaxation times T 1 and T 2 have been determined along with new high temperature measurements of the uniform susceptibility χ(0). Both K and ν Q are shown to be proportional to χ(0), with temperature the implicit parameter. T 1 and T 2 are temperature independent well above T c and their magnitudes cannot be explained by the fluctuations of localized moments. The results of all of our measurements are in general accord with the predictions of the renormalized RPA theory of spin fluctuation phenomena in itinerant magnets of Moriya and his collaborators.