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

Abstract

In contrast to hole-doped systems which have hole pockets centered at $(\pm \frac{\ddot{I}}{€}2a,\pm \frac{\ddot{I}}{€}2a)$, in lightly electron-doped antiferromagnets the charged quasiparticles reside in momentum space pockets centered at $(\frac{\ddot{I}}{€}a,0)$ or $(0,\frac{\ddot{I}}{€}a)$. 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.

25 pages, 7 figures