A Final Answer on How High-Temperature Superconductors Don't Work?

A Final Answer on How High-Temperature Superconductors Don't Work?: Tiny vibrations called phonons—the essential ingredient in the mechanism behind ordinary superconductors-play no significant role in high-temperature superconductivity, the team claims...

But theorists say phonons do not pull hard enough to keep electrons paired at the sky-high temperatures—which are still far below the freezing point of water—achieved in high-temperature superconductors. Instead, many think the glue originates in interactions among the electrons themselves, such as waves of magnetism called spin fluctuations...

The team hit the sample with a one-two punch of laser pulses roughly 100 millionths of a nanosecond, or 100 femtoseconds, long. The first pulse stirred up the electrons in the material; the second pulse measured how much the material's reflectivity had changed. The team was also able to trace the reaction not only in time, but also as a function of the frequency of the reflected light...

The ability to study the reflectivity at different wavelengths was key, Giannetti says. That's because the ultrafast electron-electron processes were too fast to observe in the time traces. However, those processes affect the reflectivity at different wavelengths in different ways—100 femtoseconds after the pulse the material was less reflective at longer wavelengths and more reflective at shorter wavelengths. Taken all together, the data show that phonons aren't needed to explain BSCCO's superconductivity, Giannetti says. Electron-electron interactions are strong enough to do the job all by themselves.