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arXiv · 1606.07449

Universal behavior of coupled order parameters below three dimensions

Julia Borchardt·Astrid Eichhorn
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Abstract

We explore universal critical behavior in models with two competing order parameters, and an O(N)+O(M) symmetry for dimensions $d \leq 3$. In d=3, there is always exactly one stable Renormalization Group fixed point, corresponding to bicritical or tetracritical behavior. Employing novel, pseudo-spectral techniques to solve functional Renormalization Group equations in a two-dimensional field space, we uncover a more intricate structure of fixed points in d<3, where two additional bicritical fixed points play a role. Towards d=2, we discover ranges of N=M with several simultaneously stable fixed points, indicating the coexistence of several universality classes.

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Julia Borchardt, Astrid Eichhorn. 2016-06-23. Universal behavior of coupled order parameters below three dimensions. https://doi.org/10.1103/physreve.94.042105

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