Pressure-Induced Superconductivity in Europium Metal

TL;DR

This study demonstrates that europium metal becomes superconducting under high pressure, with Tc reaching 2.75 K at 142 GPa, marking it as the 53rd elemental superconductor, and explores the pressure-induced change in its electronic state.

Contribution

It provides experimental evidence of pressure-induced superconductivity in europium metal, revealing a transition from magnetic to non-magnetic state at high pressures.

Findings

Eu becomes superconducting at ~80 GPa with Tc = 1.8 K

Tc increases linearly with pressure up to 2.75 K at 142 GPa

Eu is now the 53rd known elemental superconductor

Abstract

Divalent Eu (4f7, J=7/2) possesses a strong local magnetic moment which suppresses superconductivity. Under sufficient pressure it is anticipated that Eu will become trivalent (4f6, J=0) and a weak Van Vleck paramagnet, thus opening the door for a possible superconducting state, in analogy with Am metal (5f6, J=0) which superconducts at 0.79 K. We present ac susceptibility and electrical resistivity measurements on Eu metal for temperatures 1.5 - 297 K to pressures as high as 142 GPa. At approximately 80 GPa Eu becomes superconducting at Tc = 1.8 K; Tc increases linearly with pressure to 2.75 K at 142 GPa. Eu metal thus becomes the 53rd known elemental superconductor in the periodic table.