Project description
Objective O1
Synthesis and characterization of single-phase polycrystalline Mn-based HEO
I propose to synthesize, through solid states chemical synthesis method, a single-phase polycrystalline Mn-based HEO. The oxide powders: MnO2, CrO2, NiO2, CoO, Fe2O3, Nd2O3, will be mixed according to the molar ratio intended to achieve the mentioned stoichiometry (equimolar cationic ratios) and then will be grinded to a fine homogeneous mixture. This mixture will consecutively be sintered three times, in a furnace at very high temperatures like 1400℃ for 12 hours each. The individual oxides and the mixture will initially be characterized by powder diffractometer and SEM-EDX. The final product will be divided into two parts. One part will be used to make sintered pallet for PLD deposition and the other part will be used for transport measurements such as magnetometry. Once, the polycrystalline single-phase perovskites have been synthesized; we shall try to grow them in a single crystalline form. The samples will then be characterized using Single-crystal XRD and SEM-EDX. We shall try to obtain epitaxially grown thin films from the manganite powders using already optimized recipes, used for growing Nd1-x(Ca1-ySry)xMnO3 on 001-oriented SrTiO3 and 001-oriened (LaAlO3)0.3(Sr2TaAlO6)0.7. We shall try to obtain epitaxially grown heterostructures containing the manganites and YBCO.
Objective O2
Preparation and characterization of single crystalline HEO-1
In the first instance we shall analyze the growing conditions of such a complex material then, if possible, we shall find the best method to grow the polycrystals. However, in order to understand better the eventual constrains, we shall study these materials with less transitional metals in its chemical formula and characterize them in powder/crystal form.
Objective O3
Measurement of Physico-chemical properties
On the manganites, we will perform magnetometry using VSM and measurements of electrical properties using quantum-design PPMS. Element specific and microscopic information on the orbital occupancy and valency of the constituting cations will be studied by X-ray absorption/emission/fluorescence spectroscopy (XAS). Since these samples will contain five cations and oxygen, it would be very interesting to observe the fluctuation of Fermi level and valence band chemical properties from the conducting samples at a much more local scale. This can be performed with Photo-Emission Electron Microscope (PEEM) technique. Proposals will be written at synchrotron facilities like SLS (Paul Scherrer Institute), Bessy II (Berlin) and ESRF (Grenoble). Subsequently, we shall study the proximity effect on the cuprate layers in the cuprate/Mn-HEO heterostructure by means of transport measurements as well as resonant elastic/inelastic X-ray scattering in conjunction with XAS measurement at Cu-L3 edge. One of the main focuses of this study will be to investigate the copper charge density waves (Cu-CDW) in these samples and compare them with those observed in simpler manganite/cuprate heterostructures.