Discovery of an intrinsic non-Hermitian phase transition in a bulk condensed-matter system
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—undergoes 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 europium monoxide. 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.
Authors
- Shovon Pal (ORCID: https://orcid.org/0000-0002-1222-9852)
- Masakazu Matsubara (ORCID: https://orcid.org/0000-0001-5376-7414)
- Johann Kroha (ORCID: https://orcid.org/0000-0002-3340-9166)
- Michael Turaev
- Manfred Fiebig (ORCID: https://orcid.org/0000-0003-4998-7179)
- Cornelius Krellner (ORCID: https://orcid.org/0000-0002-0671-7729)
- Kristin Kliemt (ORCID: https://orcid.org/0000-0001-7415-4158)
- Jingwen Li (ORCID: https://orcid.org/0000-0002-6416-3648)
Institutions
- Goethe University Frankfurt (DE)
- University of Bonn (DE)
- Osaka University of Economics (JP)
- National Institute of Science Education and Research (IN)
- University of St Andrews (GB)
- Tohoku University (JP)
- ETH Zurich (CH)
- Japan Science and Technology Agency (JP)
- The University of Osaka (JP)
Publication Details
- Journal
- Science
- Published
- 2026-09-10
- DOI
- https://doi.org/10.1126/science.ady4670
- Citations
- 1
- Primary Topic
- Quantum Mechanics and Non-Hermitian Physics
- Type
- article
- Field-Weighted Citation Impact
- 4.30
Funders
- Deutsche Forschungsgemeinschaft
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Japan Society for the Promotion of Science
- Science and Engineering Research Board
- Japan Science and Technology Agency