Discovery of an intrinsic non-Hermitian phase transition in a bulk condensed-matter system

Abstract:Across regular phase transitions, systems remain in thermal equilibrium. However, when a system is driven far from equilibrium, non-Hermitian phase transitions may arise where the dynamical behavior rather than steady properties undergo a qualitative change at a critical, so-called exceptional point. We experimentally realize a non-Hermitian phase transition in a bulk condensed-matter system. Optical excitation creates charge carriers in ferromagnetic EuO. In a temperature-dependent interplay with the Hermitian transition to ferromagnetic order, a non-Hermitian change of the relaxation dynamics occurs, manifesting in our time-resolved reflection data as the transition from biexponential real to single-exponential complex decay. Our theory models this behavior and suggests that non-Hermitian phase transitions may generically emerge in bulk condensed matter.

Strongly Correlated Electrons (cond-mat.str-el); Statistical Mechanics (cond-mat.stat-mech); Quantum Physics (quant-ph)

arXiv:2412.16012 [cond-mat.str-el]

(or arXiv:2412.16012v2 [cond-mat.str-el] for this version)

https://doi.org/10.48550/arXiv.2412.16012 Focus to learn more arXiv-issued DOI via DataCite

https://doi.org/10.1126/science.ady4670 Focus to learn more DOI(s) linking to related resources

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