Ising-like Spin Anisotropy and Competing Antiferromagnetic - Ferromagnetic Orders in GdBaCo_{2}O_{5.5} Single Crystals

TL;DR

This paper investigates the magnetic anisotropy and spin order in GdBaCo_{2}O_{5.5} single crystals, revealing Ising-like spins and a link between oxygen ordering and magnetic properties, relevant for magnetotransport understanding.

Contribution

It uncovers the uniaxial anisotropy of Co^{3+} spins and the spin-state order linked to oxygen arrangement in GdBaCo_{2}O_{5.5}, providing new insights into magnetic structure.

Findings

Uniaxial anisotropy of Co^{3+} spins linked to oxygen order

Development of spin-state order with alternating Co^{3+} states

Magnetic structure of weakly coupled ferromagnetic ladders

Abstract

In RBaCo_{2}O_{5+x} compounds (R is rare earth), a ferromagnetic-antiferromagnetic competition is accompanied by a giant magnetoresistance. We study the magnetization of detwinned GdBaCo_{2}O_{5.5} single crystals, and find a remarkable uniaxial anisotropy of Co^{3+} spins which is tightly linked with the chain oxygen ordering in GdO_{0.5} planes. Reflecting the underlying oxygen order, CoO_2 planes also develop a spin-state order consisting of Co^{3+} ions in alternating rows of S=1 and S=0 states. The magnetic structure appears to be composed of weakly coupled ferromagnetic ladders with Ising-like moments, which gives a simple picture for magnetotransport phenomena.