Nematicity is a new piece in a phase diagram puzzle

Time：2022-01-20 11:58 Clicks：

Although twisted sheets of double bilayer graphene have been studied extensively the past few years, there are still pieces missing in the puzzle that is its phase diagram -- the different undisturbed, ground states of the system. Writing in Nature Physics, Carmen Rubio-Verdú and colleagues have found a new puzzle piece: an electronic nematic phase.

First described in another state of matter called a liquid crystal, a nematic phase occurs when particles in a material break an otherwise symmetrical structure and come to loosely orient with one another along the same axis. This phenomenon is the basis of the LCD display commonly used in televisions and computer monitors. In an electronic nematic phase, the particles in question are electrons, whose behavior and arrangement in a material can influence how well that material will conduct an electrical current in different directions.

"The data are amazing," says co-author Rafael Fernandes, a theoretical physicist at the University of Minnesotawho met senior author Abhay Pasupathy as a postdoc at Columbia. "You can clearly see that there's a symmetry being broken."