'Carpet' growth method yields long-sought 2D quantum material

For decades, physicists have sought a practical two-dimensional topological insulator: an ultrathin material whose interior blocks electricity but whose edges conduct it. In ordinary wires, electrons constantly bounce off imperfections, losing energy. But along the edges of a 2D topological insulator, electrons with opposite spins travel in opposite directions, like cars in one-way lanes, so they rarely scatter and lose energy.