Abstract-Using polarized neutron reflectometry (PNR) we measured the neutron spin dependent reflectivity from four LaAlO 3 /SrTiO 3 superlattices. This experiment implies that the upper limit for the magnetization induced by an 11 T magnetic field at 1.7 K is 2 emu/cm 3 . SQUID magnetometry of the superlattices sporadically finds an enhanced moment, possibly due to experimental artifacts. These observations set important restrictions on theories which imply a strongly enhanced magnetism at the interface between LaAlO 3 and SrTiO 3 .

We measured the chemical and magnetic depth profiles of a single crystalline (La(1-x)Pr(x))(1-y)Ca(y)MnO(3-δ) (x=0.52±0.05, y=0.23±0.04, δ=0.14±0.10) film grown on a NdGaO(3) substrate using x-ray reflectometry, electron microscopy, electron energy-loss spectroscopy, and polarized neutron reflectometry. Our data indicate that the film exhibits coexistence of different magnetic phases as a function of depth. The magnetic depth profile is correlated with a variation of chemical composition with depth. The thermal hysteresis of ferromagnetic order in the film suggests a first-order ferromagnetic transition at low temperatures.

Using polarized neutron reflectometry (PNR), we observe an induced magnetization of 75± 25 kA/m at 10 K in a La0.7Sr0.3MnO3 (LSMO)/BiFeO3 superlattice extending from the interface through several atomic layers of the BiFeO3 (BFO). The induced magnetization in BFO is explained by density functional theory, where the size of bandgap of BFO plays an important role. Considering a classical exchange field between the LSMO and BFO layers, we further show that magnetization is expected to extend throughout the BFO, which provides a theoretical explanation for the results of the neutron scattering experiment. PACS numbers: 75.70.Cn, 75.30.Et, 77.55.Nv, 78.70.Dm Introduction. Hybrid complex oxide nanostructures with controlled geometry and dimensionality provide an unprecedented platform to introduce and explore competing physical phenomena in functional materials. In particular, artificially engineered epitaxial heterostructures enable new functionalities that cannot be realized with the individual constituents. Since functionality is derived from the interactions across interfaces [1], an understanding of the interfacial structure and properties is critically important to achieve the goal of prediction and control of the properties. Experimental results [2][3][4][5] have shown that either structural or electrostatic boundary conditions can be dominant factors in controlling the atomic, electronic, and magnetic structures of interfaces in solid-solid. The availability of various heterostructures formed by different correlated electron materials offers new opportunities for studying competing interactions between different properties (charge-ordered, ferroelectric (FE), ferromagnetic (FM), and superconducting states) at interfaces. Noteworthy emergent behaviors at the interface between otherwise strongly insulating materials, like LaAlO 3 and SrTiO 3 , which arises from possible polar discontinuities at the interfaces [3][4][5][6][7] and/or chemical intermixing across the interfaces [8][9][10]. The formation of an enhanced canted magnetic state in the antiferromagnet (AFM) BiFeO 3 (BFO) at the interface with ferromagnetic La 0.7 Sr 0.3 MnO 3 (LSMO) is another intriguing observation [11,12]. Even though x-ray magnetic circular dichroism (XMCD) measurements have demonstrated exchange coupling between the ferromagnetic LSMO and antiferromagnetic BFO mediated through an enhanced magnetic state localized at the interface [11], quantitative measurements to test theoretical models are lacking. In this Letter, we report such measurements of the interface magnetism and explain its origin using density functional theory together with an effective

The room temperature chemiresistive response of n-type ZnO nanowire (ZnO NWs) films modified with different thicknesses of p-type cobalt phthalocyanine (CoPc) has been studied. With increasing thickness of CoPc (>15 nm), heterojunction films exhibit a transition from n- to p-type conduction due to uniform coating of CoPc on ZnO. The heterojunction films prepared with a 25 nm thick CoPc layer exhibit the highest response (268% at 10 ppm of H2S) and the fastest response (26 s) among all samples. The X-ray photoelectron spectroscopy and work function measurements reveal that electron transfer takes place from ZnO to CoPc, resulting in formation of a p-n junction with a barrier height of 0.4 eV and a depletion layer width of ∼8.9 nm. The detailed XPS analysis suggests that these heterojunction films with 25 nm thick CoPc exhibit the least content of chemisorbed oxygen, enabling the direct interaction of H2S with the CoPc molecule, and therefore exhibit the fastest response. The improved response is attributed to the high susceptibility of the p-n junctions to the H2S gas, which manipulates the depletion layer width and controls the charge transport.

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