Magnetic phase separation in LaMn1-xFexO3+y
Abstract
We have investigated the LaMn1-xFexO3+y system in the whole range of 0<=x<=1, for polycrystalline samples prepared by solid state reaction in air. All samples show orthorhombic structure (space group Pnma). For x=0 the oxygen excess, estimated to be y ∼ 0.1, produces vacancies in the La and Mn sites and generates a fraction around 20% of Mn^4+ ions (3t2g) and 80% of the usual Mn^3+ ions (3t2g, 1eg), with possible double exchange interaction between them. The Fe-doping in this system is known to produce only stable Fe^3+ ions (3t2g, 2eg). We find an evolution from a fairly strong ferromagnetic (FM) behavior, with saturation magnetization (T=2K) mS ∼ 4 μB and Curie temperature Tc ∼ 160 K, for x=0, to an antiferromagnetic (AFM) behavior, with TN=790 K, for x=1. For intermediate Fe contents a mixed phase scenario occurs, with a gradual decrease (increase) of the FM (AFM) phase, accompanied by a systematic transition broadening for 0.2<x<0.7. A calculation based on the expected exchange interaction among the various magnetic-ion types, accounts very well for the mS dependence on Fe doping.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2008
- Bibcode:
- 2008APS..MAR.K1061D