Researchers have created a method to manage electronic friction in devices, potentially leading to more efficient technology. By using specific materials and applying pressure or voltage, they can reduce or eliminate this hidden energy loss. The breakthrough focuses on electron interactions in smooth surfaces.
Friction typically hinders motion and wastes energy in machines, but even perfectly smooth surfaces can experience a subtler form known as electronic friction, caused by interactions among electrons. Zhiping Xu at Tsinghua University in China and his team have engineered a device to address this issue, consisting of graphite layered with a semiconductor made from molybdenum disulphide or boron nitride. These materials minimize mechanical friction, allowing isolation of the electronic component.
The team confirmed electronic friction by examining energy loss tied to electron states in the semiconductor during sliding. They found that applying pressure causes electrons between layers to share states, fully stopping the friction. Similarly, introducing a bias voltage regulates the agitation of the electron 'sea,' effectively turning off the effect.
For finer adjustments, varying voltage across different device sections acts like a dial, weakening friction without complete elimination. Xu explains, “Even when surfaces slide perfectly, mechanical motion can still stir up the ‘sea’ of electrons within the materials.”
Jacqueline Krim at North Carolina State University notes that early observations of electronic friction emerged in 1998 using superconductors at low temperatures. She envisions practical applications, such as real-time friction control via external fields, akin to adjusting shoe soles with a smartphone app for varying surfaces like ice to carpet. “The goal is this real-time remote control with no down time or material waste,” Krim says.
Xu acknowledges challenges in modeling all friction types mathematically but highlights the method's promise where electronic friction dominates energy waste or wear in devices.