Superconductivity of americium.
The metal americium becomes superconducting at temperatures as high as 0.79 K for the room temperature, double-hexagonal-close-packed phase. We also have evidence of a slightly higher transition temperature for the face-centered-cubic phase. This discovery of superconductivity in the midst of nonsuperconducting manmade elements is somewhat surprising.
Smith
J L
JL
Haire
R G
RG