Abstract
Onset of two-dimensional (2D) ferromagnetic (FM) short-range order with T 2D ≃150 K above A-type antiferromagnetic (AF) Néel temperature T N = 139 K was observed in 100 G low field for orbital-ordered LaMnO 3 . The A-type AF long-range order is stabilized through strong 2D basal plane FM superexchange coupling of orbital-ordered e g electrons and weak c-axis AF coupling. Both T 2D and T N are field dependent, and merge in 1 T high field around 130 K. Mn K-edge X-ray absorption near-edge spectrum for orbital-ordered LaMnO 3 at room temperature indicates a pre-edge splitting of 2.0 eV due to weakly allowed 1s-3d dipole transition. © 2003 Elsevier Science B.V. All rights reserved.