Phase inhomogeneity of the itinerant ferromagnet MnSi at high pressures

The pressure induced quantum phase transition of the weakly ferromagnetic metal MnSi is studied using zero-field Si-29 NMR spectroscopy and relaxation. Below P*approximate to1.2 GPa, the intensity of the signal and the nuclear spin-lattice relaxation are independent of pressure, even though the amplitude of the magnetization drops by 20% from the ambient-pressure amplitude. For P>P*, the decreasing intensity within the experimentally detectable bandwidth signals the onset of an inhomogeneous phase that persists to the highest pressure measured, Pgreater than or equal to1.75 GPa, which is well beyond the known critical pressure P-c=1.46 GPa. Implications for the non-Fermi liquid behavior observed for P>P-c are discussed.