{\beta}-YbAlB4: a critical nodal metal

TL;DR

This paper introduces a theoretical model explaining the quantum criticality of {eta}-YbAlB4 through a momentum-space vortex, resulting in a line defect that influences the material's Fermi surface and density of states.

Contribution

It proposes a novel model linking momentum-space vortices to quantum criticality and topological features in {eta}-YbAlB4, highlighting a new type of Fermi surface singularity.

Findings

Identifies a vortex in momentum space causing a line defect in hybridization.

Predicts a quasi-two-dimensional Fermi surface with a singular density of states.

Discusses implications for quantum criticality and topology.

Abstract

We propose a model for the intrinsic quantum criticality of {\beta}-YbAlB4, in which a vortex in momentum space gives rise to a new type of Fermi surface singularity. The unquenched angular momentum of the |J = 7/2,m_J = \pm5/2> Yb 4f-states generates a momentum-space line defect in the hybridization between 4f and conduction electrons, leading to a quasi-two dimensional Fermi surface with a k\perp4 dispersion and a singular density of states proportional to E^{-1/2}. We discuss the implications of this line-node in momentum space for our current understanding of quantum criticality and its interplay with topology.