Influence of Thermal Fluctuations of Spin Density Wave Order Parameter on the Quasiparticle Spectral Function

TL;DR

This paper investigates how thermal fluctuations of the spin density wave order parameter affect the quasiparticle spectral function in a 2D electron system, revealing temperature-dependent spectral broadening and Fermi surface arc restoration.

Contribution

It introduces a model analyzing the impact of thermal fluctuations on spectral density and Fermi surface features in itinerant electron systems with antiferromagnetic order.

Findings

Spectral line width scales linearly with temperature.

Thermal fluctuations transfer spectral weight into the magnetic Brillouin zone.

Fermi surface arcs are effectively restored due to fluctuations.

Abstract

The two-dimensional model of itinerant electrons coupled to an anti-ferromagnetic order parameter is considered. In the mean field solution the Fermi surface undergoes reconstruction, and breaks into disconnected ``pockets''. We have studied the effect of the thermal fluctuations of the order parameter on the spectral density in such system. These fluctuations lead to a finite width of the spectral line scaling linearly with temperature. Due to the thermal fluctuations the quasi-particle spectral weight is transfered into a magnetic Brillouin zone. This can be interpreted as restoration of ``arcs'' of the non-interacting Fermi surface.