Researchers identify phase coherence as bottleneck for superconductivity

Researchers at Utrecht, Leiden, and Munich Publish Room-Temperature Superconductivity Findings in Science

Scientists leading a joint research initiative across Utrecht University, Leiden University, and LMU Munich published findings in the journal Science, identifying a key requirement for achieving superconductivity at room temperature. Mirage News reported that the work addresses why conventional theories fail to account for high-temperature superconductors discovered since the mid-1980s.

Eliminating Resistance Entirely Through Superconductivity

When current flows through a standard metal wire, resistance converts electrical energy into heat. While useful in appliances like toasters, resistance causes energy loss when charging electronics. Superconductivity eliminates resistance entirely, enabling lossless electricity transport. However, conventional superconductors require extreme cooling to approximately -260°C using liquid helium, while higher-temperature materials discovered in the mid-1980s still require cooling to roughly -173°C.

We don’t understand superconductivity at these higher temperatures at all, said Ingmar Swart, one of the research leaders. And if you don’t understand it, you can’t systematically search for materials that become superconducting at room temperature, which is ultimately our goal.

Electron Pairing Versus Synchronous Movement in High-Temperature Materials

Superconductivity relies on two core ingredients: the formation of electron pairs known as Cooper pairs, and phase coherence, which is the synchronous movement of those pairs. In conventional low-temperature superconductors, pairing and coordination happen simultaneously. The new study reveals that this synchronization rule breaks down in high-temperature materials.

According to the research team, electrons form pairs at temperatures well above the point where superconductivity actually activates. Swart explained that the glue holding the pairs together remains functional at room temperature, which points to phase coherence as the core technical bottleneck.

Understanding superconductivity in these materials is one of the grand unsolved problems of physics, said Milan Allan, Chair of Experimental Physics – Quantum Metrology and Sensing and a research leader at LMU Munich, whose lab focuses on these dynamics.

Custom Instrumentation Built to Isolate Electrical Current Types

To capture these measurements, the research group, which also included investigators from Brookhaven National Laboratory, engineered specialized instruments in-house. Jiasen Niu, a postdoc at LMU and lead author, noted that the team has now identified the obstacles holding back higher-temperature superconductivity.

The beauty of building new instruments is that you can measure things that nobody else can measure, you can gain insights that were invisible before, said Maialen Ortego Larrazabal, who constructed key components of the hardware during her doctoral research.

The equipment enables researchers to differentiate between electrical current carried by single electrons and current carried by Cooper pairs, shedding light on the exact timing of electron pairing.