Browsing by Author "Van Tendeloo, G"

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    90° Rotation of orbital stripes in bilayer manganite PrCa2Mn2O7 studied by in situ transmission electron microscopy
    (Academic Press Inc Elsevier Science, 2013-04-01) He, ZB; Deng, G; Tian, H; Xu, Q; Van Tendeloo, G
    We present an in situ transmission electron microscopy study on the half-doped bilayer manganite PrCa2Mn2O7 to reveal the rotation process of the orbital stripes. Between the reported initial and final ordering phases, we identified an intermediate state with two sets of satellite spots to bridge the 90° rotation of the orbital stripes. Furthermore, we determined that the rotation of the orbital stripes does not always occur. Some restricted conditions for the orbital rotation to occur were found and reasons are discussed. © 2013, Elsevier Inc.
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    Local magnetic structure at the Fe3O4/ZnO interface
    (Australian Institute of Physics, 2012-02-01) Brück, S; Paul, M; Tian, H; Müller, A; Fauth, K; Goering, E; Verbeeck, J; Van Tendeloo, G; Claessen, R
    Magnetite, Fe3O4, is a half-metal with 100% spin polarization of the minority band at the Fermi level. This together with its good conductivity match to standard semiconductors makes it a promising candidate for polarized spin injection into semiconductor materials such as Si, GaAs, or ZnO [1]. An important aspect for such applications is the magnetism directly at the interface between Fe3O4 and the semiconductor. Soft x-ray resonant magnetic reflectometry is a technique which is capable of providing structural and magnetic depth profiles with 0.1nm resolution. We present a detailed XRMR and electron energy loss spectroscopy (STEM/EELS) study of an epitaxial Fe3O4 thin film grown directly on a semiconducting ZnO substrate [2]. Consistent chemical profiles at the interface between ZnO and Fe3O4 are found from XRMR and EELS. The magnetic depth profile of tetragonal Fe3+ and octahedral Fe2+ ions in Fe3O4 is derived with monolayer resolution and reveals a change in the Fe stoichiometry directly at the interface.
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    Microstructure of bilayer manganite PrCa2Mn2O7 showing charge/orbital ordering
    (American Institute of Physics, 2013-05-27) He, ZB; Tian, H; Deng, G; Xu, Q; Van Tendeloo, G
    The microstructure of the charge/orbital ordering Ruddleden-Popper phase PrCa2Mn2O7 was studied by transmission electron microscopy along both the [001] and the [110] orientation. Three coexisting charge/orbital ordering phases CO1, CO2, and CO3 were observed along the [001] orientation at room temperature. Different from the one-dimensional modulation in the CO1 and CO2 phase, the CO3 phase is characterized by two sets of mutually perpendicular structural modulations. From [110] high angle annular dark field-scanning transmission electron microscopy, we found that the Pr atoms locate in-between the bilayer MnO6 octahedra, which is different from the previous reports. © 2013, American Institute of Physics.