Pressure-Induced Superconducting State of Europium Metal at Low Temperatures

M. Debessai; T. Matsuoka; J. J. Hamlin; J. S. Schilling; K. Shimizu

doi:10.1103/PhysRevLett.102.197002

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Pressure-Induced Superconducting State of Europium Metal at Low Temperatures

M. Debessai, T. Matsuoka, J. J. Hamlin, J. S. Schilling, K. Shimizu

DOI 10.1103/PhysRevLett.102.197002 · Physical Review Letters

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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.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Eu Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.8	80 GPa	onset
Eu Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2.75	142 GPa	midpoint
Eu Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.78	84 GPa	midpoint
Am Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	0.79	Pressure unresolved	unknown
Am Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2.2	6 GPa	unknown
EuIr2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3	Pressure unresolved	unknown