At an even more basic level, sets of electrons called Cooper pairs (named for Brown physicist Leon Cooper, who shared a Nobel Prize for the discovery) form superconductivity. But scientists believe there also are other electrons that are magnetically oriented and spin on their own axes like little globes; these electrons are tilted at various angles on their imaginary axes and move in a repeating, linear pattern that resembles waves, Mitrovic and her colleagues have observed.
"These funny waves most likely appear because of superconductivity, but the reason why is still unsettled," Mitrovic said.
Adding to the mystery, Mitrovic and fellow researchers, including Brown graduate student Georgios Koutroulakis and former Brown postdoctoral associate Michael Stewart, saw that the waves fluctuated under certain conditions. After nearly three years of experiments at Brown and at the national magnetic field laboratory in Grenoble, France, Mitrovic's team was able to produce the odd waves consistently when testing a superconducting material cerium-cobalt-indium5 (CeCoIn5) at temperatures close to absolute zero and at about 10 Tesla of magnetic force.
The waves appeared to be sliding, Mitrovic said. "It's as if people are yanking on the wave," she added. Mitrovic and her colleagues also observed that when more magnetic energy is added, the fluctuations disappear and the waves resume their repeating, linear patterns.
The researchers next want to understand why these fluctuations occur and whether they crop up in other superconducting material.
|Contact: Richard Lewis|