Energy transition

Shifting away from nuclear energy, expanding solar and wind power, generating energy from biomass, reducing energy consumption. Switzerland is committed to becoming climate-neutral by 2050. An ambitious goal, which has become more urgent than ever due to the increasingly challenging geopolitical situation. How can a sustainable and resilient energy supply for Switzerland be established over the coming years? What's the optimal way to use renewable energy sources? What new technologies are especially promising? At PSI, researchers are seeking answers to these crucial questions.

Magnetic nano-rods, arranged on the sides of a hexagon (bottom) or several hexagons (middle and top), form the ring systems studied by the scientists. Several linked rings serve as a model for a frustrated system: regardless of how the magnetisation of the central rod is oriented, energetically unfavourable conditions always arise, i.e. two north poles or two south poles will inevitably meet one another - marked in yellow.

Tiny Magnets as a Model System

Scientists use nano-rods to investigate how matter assembles

In the microscopic world, everything is in motion: atoms and molecules vibrate, proteins fold, even glass is a slow flowing liquid. And during each movement there are interactions between the smallest elements - for example, the atoms - and their neighbours. To make these movements visible, scientists at the Paul Scherrer Institute PSI have developed a special model system.

Atomic motions untangled

The pursuit of capturing motion in a movie bears an obvious fascination irrespective of the time scales involved. In the atomic and molecular world where the masses are so light and the distances small the relevant time scale shifts to the ubpicosecond range and the motions become frantic especially for larger molecular systems

Schematic view of the femtosecond laser pump/x-ray probe
experiment performed at the FEMTO slicing source identifying the atomic motion coupled to the charge and orbital order in a manganite.

Atomic motions untangled

The pursuit of capturing motion in a movie bears an obvious fascination irrespective of the time scales involved. In the atomic and molecular world where the masses are so light and the distances small the relevant time scale shifts to the subpicosecond range and the motions become frantic especially for larger molecular systems.

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.