Electronic behavior of three oxygen non-stoichiometric Fe4+/Fe3+ oxoperovskites

Weak ferromagnetic ordering in brownmillerite Ca2Fe2O5 and its effect on electric field gradients

Electric field gradients in weakly ferromagnetic CaFe₂O₅ remarkably change below T_N, because of local electric polarizations induced by Dzyalosinskii-Moriya interactions.

Neutron Laue diffraction study of the complex low-temperature magnetic behaviour of brownmillerite-type Ca2Fe2O5

The atomic and magnetic structure of brownmillerite Ca2Fe2O5has been refined against single-crystal neutron Laue diffraction data collected at 300, 100 and 10 K under zero-field and low-magnetic field (35 Oe = 35 × 103/4π A m−1) conditions. Ca2Fe2O5is a canted G-type antiferromagnet withPcm′n′ symmetry, the magnetic moments on Fe being directed approximately along the crystallographiccaxis at room temperature. The refinement results show clearly that this magnetic structure persists down toT= 10 K, despite a previous suggestion that an anomalous magnetic susceptibility enhancement observed in Ca2Fe2O5single crystals between 40 and 140 K might signify a reorientation of the antiferromagnetic easy axis fromctoabelow 40 K. Alternative explanations for this susceptibility anomaly are considered in terms of the evidence for partial or short-range loss of order in the anomalous regime, possibly due to the presence of multiple competing sublattice interactions.

Control of functional responses via reversible oxygen loss in La₁-xSrxFeO₃-δ films

La0.3 Sr0.7 FeO3-δ films undergo dramatic changes in electronic and optical properties due to reversible oxygen loss induced by low-temperature heating. This mechanism to control the functional properties may serve as a platform for new devices or sensors in which external stimuli are used to dynamically control the composition of complex oxide heterostructures.