[1070]

The correlated electronic structure of SrVO(3) has been investigated by angle-resolved photoemission spectroscopy using in situ prepared thin films. Pronounced features of band renormalization have been observed: a sharp kink ∼60 meV below the Fermi level (E(F)) and a broad so-called "high-energy kink" ∼0.3 eV below E(F) as in the high-T(c) cuprates, although SrVO(3) does not show magnetic fluctuations. We have deduced the self-energy in a wide energy range by applying the Kramers-Kronig relation to the observed spectra. The obtained self-energy clearly shows a large energy scale of ∼0.7 eV, which is attributed to electron-electron interaction and gives rise to the ∼0.3 eV kink in the band dispersion as well as the incoherent peak ∼1.5 eV below E(F). The present analysis enables us to obtain a consistent picture for both the incoherent spectra and the band renormalization.

To provide camouflage in non-visual range of spectrum, i.e., against NIR detection devices working in the range of 700–1500 nm, it becomes essential that camouflaging equipment should be painted/dyed with the pigments/dyes having NIR reflectance values similar to that of backgrounds in respective shades. Generally, the shades of vegetation and desert regions are confined to olive green, brown, deep brunswick green, light stone and dark stone colour, so it is required that IR reflectance values of pigment formulation must match with the IR reflectance values of these shades of the background vegetation or desert terrains. An elaborate study has been carried out on these pigment formulations coated on cotton and nylon substrate materials. The study has brought out the reflectance trend of the formulations, role of each constituent pigment on the reflectance values and effect of dilution or concentration of pigment formulation on the reflectance properties. These studies would pave the way for preparation and optimization of various formulations with respect to IR reflectance values and their use for camouflage purpose in non-visual range of electromagnetic wave length.

The ultrathin film limit has been shown to be a rich playground for unusual low dimensional physics. Taking the example of SrRuO3 which is ferromagnetic and metallic at the bulk limit, one finds that it becomes antiferromagnetic and insulating at the three monolayers limit when grown on SrTiO3. The origin of the insulating state is traced to strongly orbital dependent exchange splittings. A modest compressive strain of 1% of the SrTiO3 substrate is then found to drive the system into a highly confined two-dimensional 100% spin polarized metallic state. This metal-insulator transition driven by a modest strain could be useful in two state device applications.

Using density functional theory calculations, ultrathin films of SrVO3(d1) and SrCrO3(d2) on SrTiO3 substrates have been studied as possible multiferroics. Although both are metallic in the bulk limit, they are found to be insulating as a result of orbital ordering driven by lattice distortions at the ultrathin limit. While the distortions in SrVO3 have a first-order Jahn-Teller origin, those in SrCrO3 are ferroelectric in nature. This route to ferroelectricity results in polarizations comparable with conventional ferroelectrics.