Enhanced magnetic ordering in Sm metal under extreme pressure

The dependence of the magnetic ordering temperature ${T}_{\text{o}}$ of Sm metal was determined through four-point electrical resistivity measurements to pressures as high as 150 GPa. A strong increase in ${T}_{\text{o}}$ with pressure is observed above 85 GPa. In this pressure range, Sm ions alloyed in dilute concentration with superconducting Y exhibit giant Kondo pair breaking. Taken together, these results suggest that for pressures above $\ensuremath{\sim}85\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}\phantom{\rule{0.16em}{0ex}}\mathrm{Sm}$ is in a highly correlated electron state, like a Kondo lattice, with an unusually high value of ${T}_{\text{o}}.$ A detailed comparison is made with similar results obtained earlier on Nd, Tb, and Dy and their dilute magnetic alloys with superconducting Y.