We propose a mechanism for A-type antiferromagnetism in orthorombic LaMnO_3, compatible with the large Jahn-Teller splitting inferred from structural data. Orbital ordering resulting from Jahn-Teller distortions effectively leads to A-type ordering (antiferromagnetic in the c axis and ferromagnetic in the ab plane) provided the in-plane distorsion Q_2 is large enough, a condition generally fulfilled in existing data.
@article{arxiv.cond-mat/9710233,
title = {Joint superexchange--Jahn-Teller mechanism for A-type antiferromagnetism in $LaMnO_3$},
author = {D. Feinberg and P. Germain and M. Grilli and G. Seibold},
journal= {arXiv preprint arXiv:cond-mat/9710233},
year = {2009}
}