Light reveals internal motion in electron crystals and can trigger their melting

Scientists at the University of Maryland, ETH Zurich and other institutes have discovered that shining light on a Wigner crystal can reveal the internal motion of electrons and even trigger their melting. Wigner crystals are unique arrangements of electrons in 2D materials, similar to the ordered patterns seen in ordinary crystals, but made up of electrons instead of atoms.

Researchers utilized a device containing a single layer of tungsten diselenide (WSe2), a transition metal dichalcogenide, to observe these crystals and study their vibrations. By shining light onto the material and measuring its reflection of different wavelengths, the team found that the excitons created by the light interacted with the Wigner crystals, causing them to vibrate and distorting the crystal lattice.

This interaction led to the creation of a Wigner polaron, a hybrid of the exciton and the lattice distortion. Furthermore, the researchers discovered that by controlling the spins of the Wigner crystal through circularly polarized light, they could manipulate its internal dynamics. In addition, increasing the optical power generated a large population of excitons, which destabilized the Wigner crystal and caused its electrons to lose their ordered arrangement, effectively melting the crystal.

This method could potentially be used to induce phase transitions in Wigner crystals at a faster rate, providing new insights into their behavior and possible applications in future electronic, optoelectronic, spintronic, and quantum devices.