期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2017
卷号：114
期号：49
页码：12906-12909
DOI：10.1073/pnas.1712584114
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid–solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field H . At the transition field H s , the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length ξ ∝ | H 2 − H s 2 | − 1 / 2 . Mean-field critical exponents are predicted, since the upper critical dimension of the transition is d u = 2 . Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.
