Dynamics of the Compact, Ferromagnetic \nu=1 Edge

TL;DR

This paper studies the edge dynamics of a fully spin-polarized quantum Hall state at filling factor one, revealing two types of localized collective excitations and their potential instabilities leading to edge reconstruction.

Contribution

It identifies a new edge spin wave mode and analyzes how edge potential softening induces edge reconstruction via spin or charge density textures.

Findings

Existence of a distinct edge spin wave mode below the bulk spin wave continuum.

Both edge excitations can soften at finite wave-vectors, causing edge reconstruction.

Common models underestimate the instability leading to edge texturing.

Abstract

We consider the edge dynamics of a compact, fully spin polarized state at filling factor $\nu=1$. We show that there are two sets of collective excitations localized near the edge: the much studied, gapless, edge magnetoplasmon but also an additional edge spin wave that splits off below the bulk spin wave continuum. We show that both of these excitations can soften at finite wave-vectors as the potential confining the system is softened, thereby leading to edge reconstruction by spin texture or charge density wave formation. We note that a commonly employed model of the edge confining potential is non-generic in that it systematically underestimates the texturing instability.