Exploring Novel Quantum Criticality in Strained Graphene

TL;DR

This paper investigates how applying strain to graphene induces quantum phase transitions and critical phenomena, revealing new states like a dimerized insulator and potential pathways to unconventional superconductivity.

Contribution

It introduces a comprehensive analysis of strain-induced quantum criticality in graphene, highlighting novel phase transitions and emergent states driven by anisotropic band structure and spin fluctuations.

Findings

Strain induces a quantum phase transition in graphene.

Critical antiferromagnetic spin fluctuations cause divergent nematic susceptibility.

Large strain leads to a dimerized spin-singlet insulator state.

Abstract

Strain tuning is increasingly being recognized as a clean tuning parameter to induce novel behavior in quantum matter. Motivated by the possibility of straining graphene up to $20$ percent, we investigate novel quantum criticality due to interplay between strain-induced anisotropic band structure and critical antiferromagnetic spin fluctuations (AFSF) in this setting. We detail how this interplay drives $(i)$ a quantum phase transition (QPT) between the Dirac-semimetal-incoherent pseudogapped metal-correlated insulator as a function of strain ($\epsilon$), and $(ii)$ critical AFSF-driven divergent nematic susceptibility near critical strain ($\epsilon_{c}$) manifesting as critical singularities in magneto-thermal expansion and Gr\"uneisen co-efficients. The correlated band insulator at large strain affords realization of a two-dimensional dimerized spin-singlet state due to this interplay, and we argue how doping such an insulator can lead to a spin-charge separated metal, leading to anomalous metallicity and possible unconventional superconductivity. On a wider front, our work serves to illustrate the range of novel states realizable by strain-tuning quantum materials.