2020/05/08 by Roland Willa · 13 citations
Materials Science · Mathematics · Physics and Astronomy · #Advanced Condensed Matter Physics #Bound state #Condensed matter physics #Degeneracy (biology) #Degenerate energy levels #Formalism (music) #Geometry #Iron-based superconductors research #Mathematical analysis #Mathematics #Order (exchange) #Phase (matter) #Phase diagram #Phase transition #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Symmetry (geometry) #Upper and lower bounds #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.102.180503
published in Physical review. B./Physical review. B 102(18) (American Physical Society) · 7 pages, 4 figures, supplementary material (2 pages)
arxiv created 2020/05/08 · openalex created_date 2020/05/13 · openalex publication_date 2020/11/11 · arxiv updated 2020/11/18 · openalex updated_date 2026/08/05
Near the accidental degeneracy of two symmetry-distinct orders, i.e., where both transition temperatures almost coincide, phase interactions significantly reshape the ordering behavior. Strong attraction between the parent phases are known to induce a joint first-order transition. For weak interactions, I report a second-order transition of both primary orders, preceded by a fluctuation-driven state of matter. Due to symmetry mixing, this antecedent bound-state order exhibits unique signatures, incompatible with either parent phase. Within a field-theoretical formalism, I derive the generic phase diagram for a system with bound-state order, study its response to strain, and evaluate analytic expressions for a specific model. As the realization of a perfect degeneracy between symmetry-distinct orders is accidental by nature, interpretations of that kind---such as (d+ig)-superconducting state as a candidate for Sr2RuO4---have inarguably a weak point. The results presented here raise the plausibility for realizing such a situation by widening the degeneracy point to an extended line. Finally, I discuss how a trainable Kerr effect under strain provides strong evidence for a bound-state phase of symmetry-distinct orders.