Phase Inhomogeneity of the Itinerant Ferromagnet MnSi at High Pressures

TL;DR

This study investigates the pressure-induced quantum phase transition in MnSi using $^{29}Si$ NMR, revealing phase inhomogeneity beyond the critical pressure and discussing its implications for non-Fermi Liquid behavior.

Contribution

It provides new insights into the inhomogeneous magnetic phase of MnSi at high pressures through detailed NMR measurements, extending understanding beyond the known critical pressure.

Findings

Inhomogeneous phase persists beyond the critical pressure

NMR signal intensity decreases with pressure indicating phase inhomogeneity

Magnetization drops by 20% without loss of NMR signal at low pressures

Abstract

The pressure induced quantum phase transition of the weakly itinerant ferromagnet MnSi is studied using zero-field $^{29}Si$ NMR spectroscopy and relaxation. Below $P^*\approx 1.2GPa$, the intensity of the signal and the nuclear spin-lattice relaxation is 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, $P\ge 1.75GPa$, which is well beyond the known critical pressure $P_c=1.46GPa$. Implications for the non-Fermi Liquid behavior observed for $P>P_c$ are discussed.