The origin of ferromagnetism in the two different phases of LaMn0.5Co0.5O3: evidence from x-ray photoelectron spectroscopic studies

Core-level Mn and Co 2p x-ray photoelectron spectroscopic studies give evidence for different spin states of Mn and Co in the two different phases of the ferromagnetic compound LaMn 0.5 Co 0.5 O 3 . Ferromagnetism in the high- T c ( T c ≈230 K) phase of the compound arises from Mn 3+ -O-Mn 3+ superexchange interactions, whereas in the low- T c ( T c ≈150 K) phase Mn 4+ -O-Co 2+ superexchange interactions are responsible for the ferromagnetism.