Nature of the pressure-induced magnetic phase transition in the itinerant-electron antiferromagnetYMn2: A microscopic view

The ${}_{}{}^{119}{}_{}{}^{}\mathrm{Sn}$ high-pressure Mössbauer-effect technique on 0.5 at. % ${}_{}{}^{119}{}_{}{}^{}\mathrm{doped}$ ${\mathrm{YMn}}_2$ has been used to investigate, on a microscopic level, the nature of the pressure-induced magnetic-to-nonmagnetic phase transition in the itinerant-electron antiferromagnet ${\mathrm{YMn}}_2$. We find, in contrast to the temperature-induced first-order magnetic phase transition at ${\mathit{T}}_{\mathit{N}}$ and at ambient pressure, a strong but continuous reduction of the ordered Mn local magnetic moment in the range 0≤p<0.3 GPa, which reveals a pressure-induced second-order phase transition. In the same pressure range, we observe a change of the nature of the spin fluctuations from transversal (0≤p<0.3 GPa) to longitudinal at higher pressures. We further show evidence for short-range magnetic order in the pressure-induced nonmagnetic state (0.3≤p≤4 GPa).