Enhanced Magnetic Ordering In Sm Metal Under Extreme Pressure

The dependence of the magnetic ordering temperature T-o of Sm metal was determined through four-point electrical resistivity measurements to pressures as high as 150 GPa. A strong increase in T-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 similar to 85 GPa Sm is in a highly correlated electron state, like a Kondo lattice, with an unusually high value of T-o. A detailed comparison is made with similar results obtained earlier on Nd, Tb, and Dy and their dilute magnetic alloys with superconducting Y.