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arXiv · 2008.08431

Universality of Boundary Charge Fluctuations

Clara S. Weber·Kiryl Piasotski·Mikhail Pletyukhov·Jelena Klinovaja·Daniel Loss·Herbert Schoeller·Dante M. Kennes
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Abstract

We establish the quantum fluctuations $\Delta Q_B^2$ of the charge $Q_B$ accumulated at the boundary of an insulator as an integral tool to characterize phase transitions where a direct gap closes (and reopens), typically occurring for insulators with topological properties. The power of this characterization lies in its capability to treat different kinds of insulators on equal footing; being applicable to transitions between topological and non-topological band, Anderson, and Mott insulators alike. In the vicinity of the phase transition we find a universal scaling $\Delta Q_B^2(E_g)$ as function of the gap size $E_g$ and determine its generic form in various dimensions. For prototypical phase transitions with a massive Dirac-like bulk spectrum we demonstrate a scaling with the inverse gap in one dimension and a logarithmic one in two dimensions.

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Clara S. Weber, Kiryl Piasotski, Mikhail Pletyukhov, Jelena Klinovaja, Daniel Loss, Herbert Schoeller, Dante M. Kennes. 2020-08-19. Universality of Boundary Charge Fluctuations. https://doi.org/10.1103/physrevlett.126.016803

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