Abstract
In compounds ( is rare earth), a ferromagnetic-antiferromagnetic competition is accompanied by a giant magnetoresistance. We study the magnetization of detwinned single crystals and find a remarkable uniaxial anisotropy of spins which is tightly linked with the chain oxygen ordering in planes. Reflecting the underlying oxygen order, planes also develop a spin-state order consisting of ions in alternating rows of and 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.
- Received 19 December 2002
DOI:https://doi.org/10.1103/PhysRevLett.90.227201
©2003 American Physical Society