paper

Strange metallicity in an antiferromagnetic quantum critical model: A sign-problem-free quantum Monte-Carlo study

arXiv:2305.06421 · doi:10.1103/PhysRevB.108.085131

Abstract

We compute transport and thermodynamic properties of a two-band spin-fermion model describing itinerant fermions in two dimensions interacting via antiferromagnetic quantum critical fluctuations by means of a sign-problem-free quantum Monte-Carlo approach. We show that the phase diagram of this model indeed contains a -wave superconducting phase at low enough temperatures. However, a crucial question that arises is whether a non-Fermi-liquid metallic regime exists above exhibiting hallmark strange-metal transport phenomenology. Interestingly, we find that this version of the model describes a non-Fermi-liquid metallic regime that displays an approximately -linear resistivity above for a strong fermion-boson interaction. Using Nernst-Einstein relation, our QMC results also show that this strange metal phase exhibits a crossover from being characterized by a charge compressibility given approximately by at high temperatures to being described by a charge diffusivity consistent with the scaling at low temperatures. Therefore, our work adds support to the view that the antiferromagnetic spin-fermion model at strong coupling can be considered a minimal model that describes both unconventional superconductivity and strange metallicity, which are fundamentally interconnected in many important strongly-correlated quantum materials.

12 pages, 9 figures

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