MIT team uncovers ice-like growth of electron phases in quantum crystal

Scientists at MIT studied thin layers of erbium tritelluride, a rare-earth crystal that supports two perpendicular charge-density-wave (CDW) patterns forming a checkerboard of electronic order. Using a pair of timed laser pulses, they first shattered the CDW arrangement and then captured its recovery with time-resolved photoemission measurements. The primary CDW rebuilt smoothly across the sample, matching the textbook picture of a second-order phase transition.

In contrast, the secondary, subdominant CDW returned in discrete pockets that expanded outward, a hallmark of a first-order transition and likened to ice crystals growing in water. This dual-mechanism observation resolves a long-standing debate about competing CDWs and may inform theories on the coexistence of superconductivity, magnetism, and other exotic states in more complex materials. The research was funded by the U.S. Department of Energy, the National Science Foundation and the Gordon and Betty Moore Foundation’s EPiQS Initiative.