Singular charge fluctuations at a magnetic quantum critical point
L. Prochaska, X. Li, D. C. MacFarland, A. M. Andrews, M. Bonta, E. F. Bianco, S. Yazdi, W. Schrenk, H. Detz, A. Limbeck, Q. Si, E. Ringe, G. Strasser, J. Kono, S. Paschen
Abstract
Spin-charge entanglement Many physical properties follow characteristic scaling laws near quantum critical points, which are associated with phase transitions at absolute zero temperature. The material YbRh 2 Si 2 has an antiferromagnetic quantum critical point, where spin-related properties are expected to follow such a scaling. Unexpectedly, Prochaska et al. found that charge fluctuations follow a critical scaling as well. The researchers fabricated high-quality thin films of YbRh 2 Si 2 and used transmission spectroscopy to measure the optical conductivity of the film and infer the scaling. Their findings point to a highly entangled state of charge and spin, which may also be responsible for the strangemetal phase in this material. Science , this issue p. 285