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arXiv · 1712.07916

Excitonic Instability and Pseudogap Formation in Nodal Line Semimetal ZrSiS

A. N. Rudenko·E. A. Stepanov·A. I. Lichtenstein·M. I. Katsnelson
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Abstract

Electron correlation effects are studied in ZrSiS using a combination of first-principles and model approaches. We show that basic electronic properties of ZrSiS can be described within a two-dimensional lattice model of two nested square lattices. High degree of electron-hole symmetry characteristic for ZrSiS is one of the key features of this model. Having determined model parameters from first-principles calculations, we then explicitly take electron-electron interactions into account and show that at moderately low temperatures ZrSiS exhibits excitonic instability, leading to the formation of a pseudogap in the electronic spectrum. The results can be understood in terms of Coulomb-interaction-assisted pairing of electrons and holes reminiscent to that of an excitonic insulator. Our finding allows us to provide a physical interpretation to the unusual mass enhancement of charge carriers in ZrSiS recently observed experimentally.

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A. N. Rudenko, E. A. Stepanov, A. I. Lichtenstein, M. I. Katsnelson. 2017-12-21. Excitonic Instability and Pseudogap Formation in Nodal Line Semimetal ZrSiS. https://doi.org/10.1103/physrevlett.120.216401

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