Can hydrogen be a superconductor?

17 Jun 2002

Following a high-pressure experiment earlier this year that created that demonstrated metallic properties of hydrogen, two Cornell physicists predict that diatomic hydrogen (H2) should have a superconducting phase, but only at megabar pressures. Neil Ashcroft and C.F. Richardson believe that the nature of the superconductivity would be a modified version of the BCS process in which electrons, which normally repel each other, would form into Cooper pairs by exchanging vibrational modes (phonons) set up in the positive-ion lattice consisting of proton pairs.

When the hydrogen remains diatomic, the basic electronic structure depends on both electrons and the holes electrons leave behind, and this mitigates somewhat the normal electron-electron repulsion which works against superconductivity. Theoretical predictions of superconducting transition temperatures have been notoriously difficult to make in the past; nevertheless, the authors argue in an upcoming article in Physical Review Letters that hydrogen, of all the elements, might exhibit room-temperature superconductivity.

Looking for the trademark zero-resistance in a tiny sample contained within a diamond-anvil cell cannot be accomplished directly so far but indirect methods (using inductive techniques) might succeed, the researchers say.