Nature of the Magnetic Order in the Charge-Ordered Cuprate La$_{1.48}$Nd$_{0.4}$Sr$_{0.12}$CuO$_4$

TL;DR

This study uses polarized neutron scattering to investigate the magnetic order in a charge-ordered cuprate, revealing either a 1D collinear or a 2D noncollinear magnetic structure, and clarifying the nature of low-energy spin excitations.

Contribution

It provides new insights into the magnetic ordering in La$_{1.48}$Nd$_{0.4}$Sr$_{0.12}$CuO$_4$, distinguishing between possible models and ruling out others, advancing understanding of stripe order in cuprates.

Findings

Magnetic order is either 1D collinear or 2D noncollinear.

Low-energy spin excitations are transversely polarized.

Alternative models with 2D electronic order or 1D helical order are ruled out.

Abstract

Using polarized neutron scattering we establish that the magnetic order in La$_{1.48}$Nd$_{0.4}$Sr$_{0.12}$CuO$_4$ is either (i) one dimensionally modulated and collinear, consistent with the stripe model or (ii) two dimensionally modulated with a novel noncollinear structure. The measurements rule out a number of alternative models characterized by 2D electronic order or 1D helical spin order. The low-energy spin excitations are found to be primarily transversely polarized relative to the stripe ordered state, consistent with conventional spin waves.