Research on Covid-19

At PSI, several projects are dedicated to important research questions concerning the Sars-CoV-2 coronavirus and the resulting diseases. We provide information on activities and projects, for example on investigations of lung tissue, on the production of proteins and antibodies or on ideas for new research on Covid-19.

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HAADF STEM micrographs of YSZ thin films deposited by different methods. a) 8YSZ SP (Tdep = 370 °C; Tpa = 600 °C, 20 h), b) 8YSZ AA-CVD (Tdep = 450 °C, Tpa = 600 °C, 20 h), c) 8YSZ AA-CVD (Tdep = 600 °C, Tpa = 600 °C for 20 h), d) 3YSZ PLD (Tdep = 450 °C, pO2 = 7 Pa, Tpa = 600 °C, 1 h) with top and bottom electrode, e) 3YSZ PLD (Tdep = 450 °C, pO2 = 1 Pa, Tpa = 600 °C, 1 h), and f) 8YSZ PLD (Tdep = 700 °C, pO2 = 2.7 Pa, Tpa = 600 °C, 20 h) with top and bottom electrodes.

On Proton Conductivity in Porous and Dense Yttria Stabilized Zirconia at Low Temperature

The electrical conductivity of dense and nanoporous zirconia-based thin films is compared to results obtained on bulk yttria stabilized zirconia (YSZ) ceramics. Different thin film preparation methods are used in order to vary grain size, grain shape, and porosity of the thin films. In porous films, a rather high conductivity is found at room temperature which decreases with increasing temperature to 120 °C. This conductivity is attributed to proton conduction along physisorbed water (Grotthuss mechanism) at the inner surfaces.

Applications of laser printing for organic electronics

The development of organic electronic requires a non contact digital printing process. The European funded e-LIFT project investigated the possibility of using the Laser Induced Forward Transfer (LIFT) technique to address this field of applications. This process has been optimized for the deposition of functional organic and inorganic materials in liquid and solid phase, and a set of polymer dynamic release layer (DRL) has been developed to allow a safe transfer of a large range of thin films.

(a), (b) IR spectra showing the T dependence of the R mode in a SrTi18O3 single crystal with a ferroelectric transition at TCurie=23  K. (c), (d) Corresponding spectra of quantum paraelectric SrTi16O3.

Electric-Field-Induced Polar Order and Localization of the Confined Electrons in LaAlO3/SrTiO3 Heterostructures

With ellipsometry, x-ray diffraction, and resistance measurements we investigated the electric-field effect on the confined electrons at the LaAlO3/SrTiO3 interface. We obtained evidence that the localization of the electrons at negative gate voltage is induced, or at least enhanced, by a polar phase transition in SrTiO3 which strongly reduces the lattice polarizability and the subsequent screening. In particular, we show that the charge localization and the polar order of SrTiO3 both develop below ∼50  K and exhibit similar, unipolar hysteresis loops as a function of the gate voltage.

Artistic view of the interface between the LaAlO3 (layer on top: La atoms are yellow Al atoms are purple and O atoms are in green) and the SrTiO3 single crystal (Sr atoms are red, Ti atoms are in blue) probed with photoemission.

Soft x-ray photoelectron spectroscopy on buried complex oxide interfaces: a new method to diagnose authentic protected electronic structures

Exotic phenomena at interfaces of complex oxides are highly promising for future solid-state electronics applications. A prominent example is the interface of two wide band gap insulators formed by growing a LaAlO3 layer on TiO2-terminated SrTiO3 substrate. When the LaAlO3 thickness exceeds 3 unit cells this system undergoes a sharp insulator-to-metal transition with a two-dimensional electron gas (2DEG) appearing at the interface.

Magnetic Cluster Excitations

Magnetic clusters, i.e., assemblies of a finite number (between two or three and several hundred) of interacting spin centers which are magnetically decoupled from their environment, can be found in many materials ranging from inorganic compounds and magnetic molecules to artificial metal structures formed on surfaces and metalloproteins.