Neutron scattering experiments were performed on single crystals of layered cobalt-oxides La2−xCaxCoO4 (LCCO) to characterize the charge and spin orders in a wide hole-doping range of 0.3x0.8. For a commensurate value of x=0.5 in (H,0,L) plane, two types of superlattice reflections concomitantly appear at low temperature; one corresponds to a checkerboard charge ordered pattern of Co/Co ions an...

Charged domain walls in ferroelectric materials are of high interest due to their potential use in nanoelectronic devices. While previous approaches have utilized complex scanning probe techniques or frustrative poling here we show the creation of charged domain walls in ferroelectric thin films during simple polarization switching using either a conductive probe tip or patterned top electrodes...

Abstract Electron and scanning probe microscopy produce vast amounts of data in the form images or hyperspectral data, such as Energy Loss Spectroscopy (EELS) 4D Scanning Transmission Microscope (STEM), that contain information on a wide range structural, physical, chemical properties materials. To extract valuable insights from these it is crucial to identify physically separate regions phases...

We investigated the origin of the energy splitting observed in the resonant x-ray scattering (RXS) in manganites. Using thin film samples with controlled lattice parameters and orbital states at a fixed orbital filling, we estimated that the contribution of the interatomic Coulomb interaction relative to the Jahn-Teller mechanism is insignificant and at most 0.27. This indicates that RXS probes...

This thesis presents optical characterizations of interfaces in ferromagnetic heterostructures and thin films used for spin polarized electronic devices. In these experiments, femtosecond laser spectroscopies are exploited to investigate the interface magnetization reversal, spin precession, and band offset, which are crucial in determining the performances of spintronic devices. First, magneti...

LSMO Low Resistance High resistance The Fig.4a shows the spin valve presented previously in Fig.1 before any higher voltage was applied this corresponds to the lowest resistance state and a SVMR of 22%. Next, we apply a voltage bias of -1.5 V and the device resistance increases from 362 kOhms to 4.3 MOhms. The voltage is subsequently reduced back to the measuring value of -0.1 V and the magneto...

To understand the near-interface magnetism in manganites, uniform, ultrathin films of La0.67Sr0.33MnO3 were grown epitaxially on single crystal (001) LaAlO3 and (110) NdGaO3 substrates. The temperature and magnetic field dependent film resistance is used to probe the film’s structural and magnetic properties. A surface and/or interface related dead-layer is inferred from the thickness dependent...