In the woven basket pattern, where the strands interlace into triangles, some electrons get stuck in place, like coins wedged in the gaps of the weave. Other electrons roam freely across the whole basket, like light filling a room. Physicists have long sought the moment when these two types of electrons start to influence each other, and now it has been found in the material CsCr6Sb6.
Angle-resolved photoemission spectroscopy, a technique that knocks electrons out with light and tracks where they fly, revealed that upon cooling to minus 200 degrees Celsius, the stationary and itinerant electrons begin to resonate like two tuning forks tuned to the same note. Their combined intensity grows, and a sharp peak appears in the spectrum.
The most surprising part: the resonance switches on exactly when magnetic order appears in the material — neighboring chromium atoms align their magnetic moments in opposite directions. Usually, such ordering hinders electron resonance, but here it does the opposite: it helps. It's as if an orchestra started playing in perfect sync just as the musicians turned their backs to each other.
The discovery forces a rethink of old ideas about how stay-at-home electrons interact with traveling electrons. Perhaps a similar mechanism operates in other basket-weave lattice materials, where scientists are searching for superconductivity and unusual magnetic states.
The basket-weave lattice is named for its resemblance to the Japanese woven basket kagome: triangles connect so that each node is surrounded by six others, and electrons there can only move along the edges, getting stuck in the center.