ABSTRACT
The electronic structure and magnetic properties of SrMn0.5Fe0.5O3 powder and films grown on (1 0 0)-SrTiO3 (STO) and (1 0 0)-LaAlO3 (LAO) substrates by pulsed laser deposition (PLD) were investigated by temperature dependent magnetization and soft x-ray absorption. The results exhibit characteristics of 3d (5) Fe(3+), [Formula: see text], and 3d (3) + 3d (4) [Formula: see text] Mn(4+) at room temperature in all samples. However, the features of 3d (5) Fe(3+) and 3d (3) Mn(4+) increased significantly for SMFO/LAO at 35 K, which also displayed substantial competition between antiferromagnetic and ferromagnetic order well-above the Néel temperature of SrFeO3 (T N ~ 134 K). We attributed this to being caused by charge disproportionation resulting from ligand-hole localization, which is more favorable to take place when the sample is under compressive strain.
ABSTRACT
In the past decade, self-assembled vertical nano-heterostructures have drawn considerable attention because a high interface-to-volume ratio can be used to tailor or create functionalities. We have systematically investigated the magnetic properties of oxide heterostructures consisting of the CoFe2O4 nanopillars embedded in the BiFeO3 matrix using macroscopic magnetization measurements and element-selective soft X-ray absorption magnetic circular dichroism (XMCD) at the Co- and Fe-L2,3 edge. The magnetization and XMCD data show that the total ordered magnetic moment of Co(2+) in CoFe2O4-BiFeO3 nano-heterostructures is strongly enhanced. This study clearly indicates that the high interface-to-volume ratio vertical nanostructure creates a strong ferromagnetic and antiferromagnetic magnetic coupling via an interface. Furthermore, the magnetic coupling can be tuned in the multiferroic-ferrimagnetic self-assembled heterostructures by controlling the spacing between nanopillars.
