Tailoring higher-order van Hove singularities in non-Hermitian interface systems via Floquet engineering

Banerjee, A and Chowdhury, D and Narayan, A (2023) Tailoring higher-order van Hove singularities in non-Hermitian interface systems via Floquet engineering. In: Physical Review B, 108 (23).

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Abstract

We propose a non-Hermitian (NH) interface system formed between two NH nodal line semimetals driven by optical fields as a platform for generation and tailoring of higher-order van Hove singularities (VHS). Through an analytical analysis of the density of states (DOS), we find VHS with logarithmic divergences in the Hermitian limit. Upon introducing NH terms, four exceptional rings on two sides of the Fermi line are formed. By tuning the NH parameters and the light amplitude, we find a situation when one exceptional ring crosses the Fermi line, where a saddle point appears and results in a paired VHS around the origin. In contrast, when an exceptional contour resides at the Fermi energy, the saddle points critically get destroyed and we obtain a single peak in the DOS, with power-law divergences. These higher-order divergences that appear in an NH system have a different origin than that of the higher-order VHS in Hermitian systems, where no saddle point merging is noted. Our results suggest NH interfaces to be promising avenues for exploring higher-order VHS. © 2023 American Physical Society.

Item Type:	Journal Article
Publication:	Physical Review B
Publisher:	American Physical Society
Additional Information:	The copyright for this article belongs to the publisher.
Keywords:	Densities of state; Floquet; Hermitians; High-order; Higher-order; Interface system; Nodal line; Optical field; Saddle point; Van Hove singularities
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	02 Aug 2024 11:53
Last Modified:	02 Aug 2024 11:53
URI:	http://eprints.iisc.ac.in/id/eprint/85304

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