A rug lies flat, but if you push it from the edge, wrinkles run across it. In a thin film of tantalum sulfide (1T-TaS2), wrinkles made of electrons, charge waves, freeze as if the rug were stuck to the floor. To move them, you need to apply force. Scientists have found a way to control this force using an electric field and a magnet.
The film was placed between layers of hexagonal boron nitride, like the filling in a sandwich, with electrical contacts attached from above and below. It turned out that a weak electric field makes it easier for the waves to shift, while a strong field does the opposite: it makes them harder to move. A magnet directed perpendicular to the film raises the threshold for shifting and can force the waves to rearrange from one pattern to another.
This kind of control over charge waves could be useful for creating devices that use almost no energy to switch, and for electronics that operate in strong magnetic fields or at low temperatures.
Tantalum sulfide 1T-TaS2 is known for its charge waves forming a pattern that resembles the Star of David, visible under a scanning tunneling microscope.