Researchers at the University of Manchester have observed, for the first time, electrons in graphene that move like in a very viscous liquid, which may prompt a new approach to fundamental physics. The possibility of a highly viscous flow of electrons in metals was predicted several decades ago, but despite many efforts was never observed before.
Although it is believed that electrons in graphene can move 'ballistically', like bullets scattering only at graphene boundaries or other imperfections, it seems that the reality is not quite so simple; It was observed that the electric current in graphene did not flow along the applied electric field, as in other materials, but traveled backwards forming whirlpools where circular currents appeared. Such behavior is familiar for conventional liquids (such as water).
The team measured the viscosity of the new liquid in graphene, which consists of electrons. To the researchers' surprise, the electron fluid can be 100 times more viscous than honey, even at room temperature. The scientific breakthrough is important for understanding how materials work at increasingly small sizes required by the semiconducting industry because such whirlpools are more likely to appear at micro and nanoscale.
The observation also questions scientists' current understanding of the physics of highly conductive metals, especially graphene itself. The simultaneous existence of such seemingly incompatible properties, with electrons behaving in two contrasting ways within the same material, prompts a fundamental rethinking about the understanding of materials properties.
The researchers now need to figure out how to connect such contradictory behavior as ballistic motion of electrons, which is undoubtedly seen in graphene, with this new quantum phenomenon arising from their collective motion.