Table salt makes food taste better in the kitchen, but in the lab it helps grow crystals just a few atoms thick. Scientists took tin selenide and, with the help of salt, grew ultra-thin flakes from it, so thin they're called two-dimensional. The salt acted as a separator: it kept the flakes from clumping together and made them lie flat on the substrate, like pancakes on a griddle.
Inside these flakes, the researchers found regions that remember the direction of an applied electric field, like a compass needle remembers where north is. These regions are called ferroelectric domains, and they make the material promising for tiny memory cells: write a field, and you've stored a bit of information.
This result is not just a curiosity. It shows that two-dimensional tin selenide can be produced controllably and its unusual electrical and magnetic properties can be studied. That means such flakes could one day form the basis for memory that takes up thousands of times less space than today's memory.
Tin selenide is a close relative of a material already used in solar cells and thermoelectric generators that convert heat into electricity.