Superconductivity in Yttrium Metal at 17 K

Many of the known elemental superconductors only become superconducting if high pressure is applied. In 1970 J. Wittig [1] discovered superconductivity in yttrium metal at 1.2 K under 11 GPa pressure, $T_{c}$ increasing to 2.7 K at 16 GPa. Using a diamond-anvil cell with dense helium pressure medium, we have extended this pressure range to 89 GPa. We find that $T_{c}$ for yttrium metal reaches values as high as 17 K (ac susceptibility midpoint), one of the highest transition temperatures ever observed for an elemental superconductor. [1] J. Wittig, Phys. Rev. Lett. 24, 812 (1970).