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Fnord666 writes:

Researchers identify new type of superconductor:

Until now, the history of superconducting materials has been a tale of two types: s-wave and d-wave.

Now, Cornell researchers—led by Brad Ramshaw, the Dick & Dale Reis Johnson Assistant Professor in the College of Arts and Sciences—have discovered a possible third type: g-wave.

[...] Physicists have theorized the existence of a third type of superconductor between these two so-called "singlet" states: a p-wave superconductor, with one quanta of angular momentum and the electrons pairing with parallel rather than antiparallel spins. This spin-triplet superconductor would be a major breakthrough for quantum computing because it can be used to create Majorana fermions, a unique particle which is its own antiparticle.

For more than 20 years, one of the leading candidates for a p-wave superconductor has been strontium ruthenate (Sr2RuO4), although recent research has started to poke holes in the idea.

Ramshaw and his team set out to determine once and for all whether strontium ruthenate is a highly desired p-wave superconductor. Using high-resolution resonant ultrasound spectroscopy, they discovered that the material is potentially an entirely new kind of superconductor altogether: g-wave.

"This experiment really shows the possibility of this new type of superconductor that we had never thought about before," Ramshaw said. "It really opens up the space of possibilities for what a superconductor can be and how it can manifest itself.

[...] Based on the data, they determined that strontium ruthenate is what's called a two-component superconductor, meaning the way electrons bind together is so complex, it can't be described by a single number; it needs a direction as well.

[...] By determining that the material was two-component, Ramshaw's team not only confirmed those findings, but also showed strontium ruthenate wasn't a conventional s- or d-wave superconductor, either.

[...] Now the researchers can use the technique to examine other materials to find out if they are potential p-wave candidates.

Journal Reference:
Sayak Ghosh, Arkady Shekhter, F. Jerzembeck, et al. Thermodynamic evidence for a two-component superconducting order parameter in Sr 2 RuO 4, Nature Physics (DOI: 10.1038/s41567-020-1032-4)

Previously:
The Case of the Elusive Majorana: The So-Called 'Angel Particle' is Still a Mystery

Original Submission