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An antiferromagnet-ferromagnet-antiferromagnet trilayer was grown in magnetic field using CoMn, permalloy (Py), and FeMn, respectively. Magnetometry studies show that the direction of exchange coupling of CoMn with Py was perpendicular to that of Py with FeMn. These results are explained by a spin flop in the CoMn layer and show that the spin structure of an antiferromagnet may undergo severe modification due to a relatively small magnetic field applied during its growth. The perpendicular exchange coupling was exploited in the CoMn-Py-FeMn trilayer to manipulate the easy axis of the ferromagnet. [ABSTRACT FROM AUTHOR]

We investigate the magnetic properties of the isostructural spinel-spinel interface of NiMn2O4(NMO)–Fe3O4. Although the magnetic transition temperature of the NMO film is preserved, both bulk and interface sensitive measurements demonstrate that the interface exhibits strong interfacial magnetic coupling up to room temperature. While NMO thin films have a ferrimagnetic transition temperature of 60 K, both NiFe2O4 and MnFe2O4 are ferrimagnetic at room temperature. Our experimental results suggest that these magnetic properties arise from a thin interdiffused region of (Fe,Mn,Ni)3O4 at the interface, leading to Mn and Ni magnetic properties similar to those of MnFe2O4 and NiFe2O4. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions composed of the colossal magnetoresistance material La0.7Sr0.3MnO3 (LSMO) and magnetite (Fe3O4) have been fabricated and characterized. The films were grown on (110) SrTiO3 substrates using pulsed laser deposition, with the nonmagnetic spinel Mg2TiO4 (MTO) chosen as the barrier layer in order to provide a well lattice-matched isostructural interface with the Fe3O4 electrode. Junction magnetoresistance (JMR) values of up to -26% were observed for junctions with 50-Å-thick MTO barriers at 70 K. Measurements were performed on junctions with barrier thicknesses ranging from 50–120 Å. The resistance jumps in JMR correspond well to the switching fields of the LSMO and Fe3O4 magnetic electrodes. The magnitude of the JMR peaks and then begins to decline with decreasing temperature, indicating that prior observations of such temperature-dependent JMR behavior in CoCr2O4 barrier junctions were due to the electrode at low temperatures rather than to magnetic moments in the CoCr2O4. [ABSTRACT FROM AUTHOR]

Resonant soft x-ray absoiption measurements at the O K edge on a SrMnO3/LaMnO3 superiattice show a shoulder at the energy of doped holes, which corresponds to the main peak of resonant scattering from the modulation in the doped hole density. Scattering line shape at the Mn L3.2 edges has a strong variation below the ferromagnetic transition temperature. This variation has a period equal to half the superiattice superperiod and follows the development of the ferromagnetic moment, pointing to a ferromagnetic phase developing at the interfaces. It occurs at the resonant energies for Mn3+ and Mn4+ valences. A model for these observations is presented, which includes a double-exchange two-site orbital and the variation with temperature of the hopping frequency tij between the two sites. [ABSTRACT FROM AUTHOR]

Epitaxial La1-xSrxMnO3·SrO (x=1/3) films were synthesized as random alloys and cation-ordered analogs to probe how cation ordering affects the properties of a two dimensional manganite. The films show evidence for a spin glass like phase below 20 K and weak ferromagnetic ordering up to 130 K. There is a dramatic difference in magnetic anisotropy and the low temperature transport mechanism depending on the cation order, which is consistent with differences in Mn 3d orbital occupancies. This work indicates that cation ordering can significantly alter the Mn 3d orbital ground state in these correlated electron systems. [ABSTRACT FROM AUTHOR]

Epitaxial La1-xSrxMnO3·SrO (x=1/3) films were synthesized as random alloys and cation-ordered analogs to probe how cation ordering affects the properties of a two dimensional manganite. The films show evidence for a spin glass like phase below 20 K and weak ferromagnetic ordering up to 130 K. There is a dramatic difference in magnetic anisotropy and the low temperature transport mechanism depending on the cation order, which is consistent with differences in Mn 3d orbital occupancies. This work indicates that cation ordering can significantly alter the Mn 3d orbital ground state in these correlated electron systems. [ABSTRACT FROM AUTHOR]

(LaNiO3)n/(LaMnO3)2 superlattices were grown using ozone-assisted molecular beam epitaxy, where LaNiO3 is a paramagnetic metal and LaMnO3 is an antiferromagnetic insulator. The superlattices exhibit excellent crystallinity and interfacial roughness of less than one unit cell. X-ray spectroscopy and dichroism measurements indicate that electrons are transferred from the LaMnO3 to the LaNiO3, inducing magnetism in LaNiO3. Magnetotransport measurements reveal a transition from metallic to insulating behavior as the LaNiO3 layer thickness is reduced from five to two unit cells and suggest an inhomogeneous magnetic structure within LaNiO3. [ABSTRACT FROM AUTHOR]