Magnetic vortices instead of stripes: another interpretation of magnetic neutron scattering in lanthanum cuprates

TL;DR

This paper proposes that a vortex-like magnetic superstructure, rather than stripe order, explains the magnetic neutron scattering data in lanthanum cuprates, offering an alternative interpretation of the observed peak splitting.

Contribution

It introduces a vortex crystal model as a new interpretation for magnetic scattering in lanthanum cuprates, challenging the stripe-based explanation.

Findings

Vortex superstructure can explain the four-fold splitting of magnetic peaks.

The vortex model is magnetically stable under certain approximations.

Charge modulation consistent with experimental charge peaks is predicted.

Abstract

It is proposed, that a two-dimensional magnetic superstructure closely related to the one mentioned recently by Christensen et al. [cond-mat/0608204] constitutes a viable interpretation of the four-fold splitting of the magnetic (\pi, \pi) peak in lanthanum cuprates. (This splitting is usually interpreted as the evidence for stripes.) The superstructure in question has the topology of the square crystal of magnetic vortices with approximate periodicity (4a x 4a). This vortex crystal exhibits no magnetic antiphase lines. It is shown that such a superstructure is magnetically stable in the approximation of staggered spin polarizations, and that it should be accompanied by charge modulation characterized by charge peaks at the positions observed experimentally.