‘Strange Metals’ Could Lead to Fundamental Insights

Strange Metals

This discovery from Brown University could help scientists understand ‘strange metals’ and how they relate to the fundamental nature of reality. Strange metals or Non-Fermi liquids are unconventional metals that display the breakdown of Fermi-liquid behavior. Their physical properties deviate qualitatively from those of noninteracting fermions due to strong quantum fluctuations near Fermi surfaces. 

Scientists understand how temperature affects electrical conductance in most metals such as gold or copper. However, they do not understand the electrical conductance in strange metals because they do not seem to follow the traditional electrical rules. Understanding strange metals could help scientists understand phenomena like high-temperature superconductivity, and provide fundamental insights into the quantum world.

Superconductivity, where an electric current is transported without any losses, holds enormous potential for green technologies. For example, if it could be made to work at high enough temperatures, it could enable the lossless transport of renewable energy over great distances. Investigating this phenomenon is the aim of the research field of high-temperature superconductivity in thermal shock testing labs. 

The current record for high-temperature superconductivity stands at −130°C in a material testing lab. Although this might not seem like a high temperature, it is when compared to standard superconductors, which only work below −230°C.

While standard superconductivity is well understood, high-temperature superconductivity is still a puzzle to be solved. Strange metal states are limited to metrology testing labs and they emerge at temperatures that allow for high-temperature superconductivity. This newly published research can help us understand high-temperature superconductivity.

Now, a research team from Brown University has added a new discovery to the strange metal mix. In their research, the team found strange metal behavior in a material in which electrical charge is carried not by electrons, but by “wave-like” entities called Cooper pairs.

While electrons belong to a class of particles called fermions, Cooper pairs act as bosons, which follow very different rules from fermions. This is the first time strange metal behavior has been seen in a bosonic system, and researchers are hopeful that the discovery might help find an explanation for how strange metals work — something that has eluded scientists for decades.

“We have these two fundamentally different types of particles whose behaviors converge around a mystery,” said Jim Valles, a professor of physics at Brown and the study’s corresponding author. “What this says is that any theory to explain strange metal behavior can’t be specific to either type of particle. It needs to be more fundamental than that.”

“It’s been a challenge for theoreticians to come up with an explanation for what we see in strange metals,” Valles said. “Our work shows that if you’re going to model charge transport in strange metals, that model must apply to both fermions and bosons — even though these types of particles follow fundamentally different rules.”