Systematic Low-Energy Effective Field Theory for Electron-Doped Antiferromagnets

TL;DR

This paper develops a systematic low-energy effective field theory for electron-doped antiferromagnets, revealing unique momentum-dependent magnon-mediated forces and predicting the absence of spiral phases in these materials.

Contribution

It introduces a novel effective field theory tailored for electron-doped antiferromagnets, highlighting differences from hole-doped systems and providing new insights into their magnetic interactions.

Findings

Magnon-mediated electron forces depend on total momentum P.

One-magnon exchange potential scales as 1/r^4 at P=0.

Spiral magnetic phases are predicted to be absent.

Abstract

In contrast to hole-doped systems which have hole pockets centered at $(\pm \frac{\pi}{2a},\pm \frac{\pi}{2a})$, in lightly electron-doped antiferromagnets the charged quasiparticles reside in momentum space pockets centered at $(\frac{\pi}{a},0)$ or $(0,\frac{\pi}{a})$. This has important consequences for the corresponding low-energy effective field theory of magnons and electrons which is constructed in this paper. In particular, in contrast to the hole-doped case, the magnon-mediated forces between two electrons depend on the total momentum $\vec P$ of the pair. For $\vec P = 0$ the one-magnon exchange potential between two electrons at distance $r$ is proportional to $1/r^4$, while in the hole case it has a $1/r^2$ dependence. The effective theory predicts that spiral phases are absent in electron-doped antiferromagnets.