In the mid-1980s, physicists stumbled upon materials that could superconduct — conduct electricity with zero resistance — at far higher temperatures than ever before. The discovery triggered a global scientific frenzy, earning a Nobel prize within a year and sparking dreams of lossless power grids and levitating trains. Yet amid the excitement, a quieter puzzle emerged: even when these materials were too warm to superconduct, they still conducted electricity in a bizarre way that no existing theory could explain.
That odd behaviour, now known as 'strange-metal' behaviour, has remained an enigma for four decades. Unlike ordinary metals, whose electrical resistance follows predictable patterns based on temperature, strange metals show a linear relationship between resistance and temperature that defies the standard quasiparticle model. The quasiparticle theory, developed by Lev Landau in the 1950s, has been the bedrock of solid-state physics for 70 years, accurately predicting everything from heat capacity to magnetic susceptibility. It underpins the entire electronics industry, from smartphones to supercomputers.
According to Subir Sachdev, a theorist at Harvard University, the failure of quasiparticles to explain strange metals has forced physicists to question fundamental assumptions about how electricity flows. 'There must be something about it that gives the answer,' he says. Researchers are now exploring radical ideas, including the notion that electrons in strange metals behave more like a collective 'quantum soup' than individual particles, and even drawing parallels to the physics of black holes.
Recent experiments are finally beginning to shed light on the mystery. By studying the behaviour of electrons in these materials under extreme conditions — such as high magnetic fields and low temperatures — scientists are observing signatures that do not fit the quasiparticle picture. Instead, the results suggest that the electrons lose their individual identities and act as a unified whole, a phenomenon that could explain both the strange-metal state and its superconducting cousin.
The implications extend far beyond theoretical physics. Understanding strange metals could unlock the secret to room-temperature superconductivity, which would revolutionise energy transmission, medical imaging, and transport. For now, the work remains in the realm of fundamental research, but the findings — which are published in peer-reviewed journals — are gradually building a new framework for one of the most basic processes in the universe.