For nearly 40 years, materials called “strange metals” have puzzled quantum physicists by defying explanation by acting outside the normal laws of electricity. Now, research led by Aavishkar Patel of the Flatiron Institute’s Center for Computational Quantum Physics (CCQ) in New York has finally identified a mechanism that explains the characteristic properties of strange metals.

in the issue of the magazine Science On August 18, Patel and colleagues present their universal theory of why strange metals are so strange, a solution to one of the biggest unsolved problems in condensed matter physics.

The peculiar behavior of the metal is observed in many quantum materials, including those that can become superconductors with minor changes (materials in which electrons flow with zero resistance at sufficiently low temperatures). This link suggests that understanding strange metals could help researchers identify new types of superconductivity.

This surprisingly simple new theory explains many of the oddities about strange metals; for example, why the change in electrical resistivity (a measure of how easily electrons can flow as electric currents through a material) is directly proportional to temperature, even to extremely low temperatures. This ratio means that the strange metal resists electron flow more than an ordinary metal like gold or copper at the same temperature.

The new theory is based on the combination of two properties of strange metals. First, their electrons can become quantum-mechanically interconnected, tying their destinies, and remain entangled even if they are far apart from each other. Second, strange metals have a non-uniform arrangement of atoms, similar to patchwork.

Patel, a Flatiron Research Fellow at CCQ, says that alone cannot explain the strangeness of the strange metals, but taken together “everything falls into place.”

The irregularity of the strange metal’s atomic structure means that electron entanglement varies depending on where the entanglement occurs in the material. This variation adds randomness to the momentum of electrons moving through the material and interacting with each other. Instead of flowing together, electrons collide in all directions, creating electrical resistance. The electrical resistance increases with temperature, as the electrons collide more frequently as the material heats up.

“This interplay of entanglement and disorder is a new effect; it had not been considered for any material before,” says Patel. “Looking back, it’s such a simple thing. For a long time, people overcomplicated the whole story of strange metals, and that was completely wrong.”

Patel says a better understanding of strange metals could help physicists design and tune new superconductors for applications such as quantum computers.

“There are times when something wants to be superconducting but can’t quite do it because the superconductivity is blocked by another competing state,” he says. “Next, it may be asked whether the presence of these inhomogeneities could destroy these other states in which superconductivity competes, leaving the way open for superconductivity.”

Now that strange metals have become a little less strange, the name may seem less appropriate than before. “For now, I want to call them unusual metals, not weird,” Patel says. Source