Scientists discover that electrons flow around holes like water around stones

Would you believe that particles could flow faster when there are holes in the way? This counterintuitive idea has been borne out by a group of scientists in Spain. The key is in a unique kind of particle motion called hydrodynamic flow, in which particles move collectively like a body of fluid. This type of flow is known to occur when the interactions between the particles are much stronger than any other interactions — like collisions — that the particles face in the flow. 

In this study, the group used an atomic layer of graphite, also known as graphene, as a channel for electrons. But instead of using a uniform sheet of graphene, they introduced an array of holes with different sizes and patterns to obstruct the electrons’ path and alter the strength of their interactions. They found that the strength of the electron interactions depended on the sizes of the holes, the type of pattern, and the temperature. Hence, they discovered that the electron interaction strength could be controlled by tuning these parameters. As they decreased the temperature, the electrons began to flow hydrodynamically because the interactions between them were sufficiently enhanced. However, when the temperature was lowered beyond a certain threshold, electron interactions became so weak that electrons did not interact with each other, a phenomenon known as ‘ballistic’ flow. The electrical resistance of the holed graphene became lowest in the hydrodynamic flow and increased again as the flow became ballistic. The faster current flow is a hallmark of hydrodynamic flow known as ‘super-ballistic conduction.’

Hydrodynamic flow of electrons decreases electrical resistance, making it of great interest to engineering sectors seeking energy-efficient devices. Hydrodynamic electron flow may also enable more creative electronic devices that utilize fluid mechanical structures like the Tesla valve. The potential to apply electron hydrodynamics in pioneering technologies motivates further research that may transform electronics.

This study was led by Jorge Estrada-Alveraz, et al. from Universidad Complutense, Spain.

Managing Correspondent: Seunghyun (Elizabeth) Park

Press Article:  Holey Material Enhances Electron Flow (Physics)

Original Journal Articles: Superballistic Conduction in Hydrodynamic Antidot Graphene Superlattices (Physics Review X)

Image Credit : Jaesung An (Pixabay)