A new study by Rice University physicist Qimiao Si unravels the enigmatic behaviors of quantum critical metals—materials that defy conventional physics at low temperatures. Published in Nature Physics Dec. 9, the research examines quantum critical points (QCPs), where materials teeter on the edge between two distinct phases, such as magnetism and nonmagnetism. The findings illuminate the peculiarities of these metals and provide a deeper understanding of high-temperature superconductors, which conduct electricity without resistance at relatively high temperatures.

Key to this study is quantum criticality, a delicate state where the material becomes ultrasensitive to quantum fluctuations—microscopic disturbances that alter electron behavior. While ordinary metals obey well-established principles, quantum critical metals defy these norms, exhibiting strange and collective properties that have long puzzled scientists. Physicists call such systems “strange metals.”

“Our work dives into how quasiparticles lose their identity in strange metals at these quantum critical points, which leads to unique properties that defy traditional theories,” said Si, the Harry C. and Olga K. Wiess Professor of Physics and Astronomy and director of Rice’s Extreme Quantum Materials Alliance.