Israeli scientists show how electrons ‘flow’ like water

Israeli scientists have used a new material the thickness of an atom and an innovative new imaging system to show how electrons can “flow” like water.

The hydrodynamics of electrons – meaning how they move – has long been somewhat of a scientific mystery since the sub-atomic particles fly around faster than the human eye can observe.

Electrons are the tiny charged particles that orbit the nucleus of an atom, weighing almost 2,000 times less than each proton and neutron in the centre.

Electricity is essentially the exchange of electrons in a stream called a current through a conducting medium, so the movement of electrons is of great interest to technology firms, given society’s increasing reliance on electricity.

Although electrons are said to “flow through” materials, they do not normally move through conductors like a liquid, but rather, they tend to move more like a gas, bouncing off impurities and imperfections in the conductor.

However, scientists have suspected that a liquid-like hydrodynamic electron flow is possible, so researchers at the Weizmann Institute chose to check with the help of a unique technique to image electrons flowing similarly to water flowing through a pipe.

Their success, recorded in the journal Nature, is the first time such “liquid electron flow” has been visualised, with potential implications for future electronic devices.

To observe it they used graphene, a nano-material developed at the University of Manchester which is the thickness of one carbon atom, and which can be kept exceptionally clean.

Professor Shahal Ilani and the team at the Institute’s Condensed Matter Physics Department then imaged the electron flow by using a nanoscale detector built from a carbon nanotube transistor that can image the properties of flowing electrons with unprecedented sensitivity.

“Our technique is at least 1,000 times more sensitive than alternative methods; this enables us to image phenomena that previously could only be studied indirectly,” said Dr. Joseph Sulpizio from the Weizmann team.

The team created nanoscale “channels” designed to guide the flowing electrons, and saw the hallmark signature of hydrodynamic flow: just like water in a pipe, the electrons in the graphene flowed faster in the centre of the channels and slowed down at the walls.

Knowing that electrons can mimic the patterns of a conventional liquid may now impact the design of electronic devices, including those needing less power.

“Computing centres and consumer electronics are devouring an ever increasing amount of energy,” said Weizmann’s Dr Lior Ella. “It’s imperative to find ways to make electrons flow with less resistance.”