Charge Ordering Due to Magnetic Symmetry Breaking

TL;DR

This paper proposes that charge ordering in 50%-doped manganites is fundamentally a magnetic transition driven by magnetic symmetry breaking, involving distinct magnetic phases at different temperatures.

Contribution

It introduces a magnetic symmetry breaking framework to explain charge ordering and the associated anisotropic magnetic structures in doped manganites.

Findings

Charge ordering is linked to magnetic transitions at different temperatures.

Magnetic structure below charge ordering temperature is highly anisotropic.

Lattice distortions influence the phase transition nature.

Abstract

It is argued that both transitions observed in 50%-doped manganites, at the N\'{e}el temperature ($T_{\rm N}$) and the so-called charge ordering temperature ($T_{\rm CO}$), are magnetic. $T_{\rm N}$ corresponds to the order-disorder transition, which takes place between ferromagnetic zigzag chains, while the coherent motion of spins within the chains is destroyed only around $T_{\rm CO}$. The magnetic structure realized below $T_{\rm CO}$ is highly anisotropic. It is dressed by the lattice distortion and leads to huge anisotropy of the electronic structure, which explains stability of this state as well as the form of charge-orbital pattern above $T_{\rm N}$. The type of phase transition at $T_{\rm N}$ depends on lattice interactions.