Pseudogaps in Nested Antiferromagnets

TL;DR

This paper investigates fluctuation effects and pseudogap phenomena in 3D nested antiferromagnets like chromium, concluding that fluctuations do not induce a quantum critical point and that pseudogaps are present but smaller than spectral gaps.

Contribution

It provides a detailed analysis of fluctuation corrections and pseudogap formation in nested antiferromagnets, clarifying their roles in quantum criticality and spectral properties.

Findings

Fluctuation corrections are insufficient to cause a quantum critical point in 3D nested antiferromagnets.

A pseudogap exists in the paramagnetic phase, but is smaller than the ordered state gap.

The critical point in doped chromium is due to loss of nesting, not fluctuations.

Abstract

We analyze the fluctuation corrections to magnetic ordering in the case of a 3D antiferromagnet with flat Fermi surfaces, as physically realized in the case of chromium, and find that they are insufficient to produce a quantum critical point. This implies that the critical point observed in vandium doped chromium is due to a loss of nesting. We also derive the fermion self-energy in the paramagnetic phase and find that a pseudogap exists, though its magnitude is significantly reduced as compared to the spectral gap in the ordered state in the limit where the latter is small in comparison to the Fermi energy.