Magnetic ordering at anomalously high temperatures in Dy at extreme pressures

Abstract

In an attempt to destabilize the magnetic state of the heavy lanthanide Dy, extreme pressures were applied in an electrical resistivity measurement to 157 GPa over the temperature range 1.3--295 K. The magnetic ordering temperature ${T}_{\text{o}}$ and spin-disorder resistance ${R}_{\text{sd}}$ of Dy, as well as the superconducting pair-breaking effect $\ensuremath{\Delta}{T}_{\text{c}}$ in Y(1 at.% Dy), are found to track each other in a highly nonmonotonic fashion as a function of pressure. Above 73 GPa, the critical pressure for a 6% volume collapse in Dy, all three quantities increase sharply ($d{T}_{\phantom{\rule{4.pt}{0ex}}\text{o}}/dP\ensuremath{\simeq}5.3$ K/GPa), ${T}_{\text{o}}$ appearing to rise above ambient temperature for $P>107$ GPa. In contrast, ${T}_{\text{o}}$ and $\ensuremath{\Delta}{T}_{\text{c}}$ for Gd and Y(0.5 at.% Gd), respectively, show no such sharp increase with pressure ($d{T}_{\text{o}}/dP\ensuremath{\simeq}0.73$ K/GPa). Taken together, these results suggest that extreme pressure transports Dy into an unconventional magnetic state with an anomalously high magnetic ordering temperature.