Notizie

Resonant inelastic x-ray scattering reveals that lattice vibrations can be chiral in a polar material, with phonons having opposite handedness depending on their direction in momentum space.

Across the fields of magnetism, microelectronics, optics, and others, engineered local variations in material properties can yield groundbreaking functionalities that play a crucial role in enabling future technologies. One-dimensional lateral gradients in material properties give rise to a plethora of new effects in thin-film magnetic systems. However, extending such gradient-induced behaviors to two dimensions has been challenging to realize experimentally. Here, we demonstrate the creation of two-dimensional complex patterns with continuous variations in magnetic anisotropy, interlayer exchange coupling, and ferrimagnetic compensation at the mesoscopic scale in numerous application-relevant magnetic materials. We exploit our engineered gradients in material properties to demonstrate novel magnetic functionalities, including the creation of a spin wave band pass filter and an architecture for passively resetting the position of a magnetic domain wall. Our results highlight the exciting new physics and device applications enabled by two-dimensional gradients in thin film properties.

We quantify “how chiral” a crystal is, and demonstrate its tunability at ultrafast timescales. This achievement does open up a new direction in chirality-related condensed matter physics and on emergent phenomena, which have both attracted significant attention recently.

The 2D self-arrangement of a molecule that resembles three-armed spirals leads to a triangular pattern that is effectively aperiodic.

X-ray magnetic circular dichroism (XMCD) is a magneto-optical effect that describes the difference in absorption between left and right circularly polarized X-rays by a magnetized material. It has been widely applied to the study of magnetic systems and of magnetic phenomena and its unique capabilities make it a fundamental tool for the study of novel magnetic phenomena and new materials systems.

Transmission electron and soft x-ray microscopy have contributed significantly to our understanding of phenomena in fields ranging from biology to materials science. In this review, we present recent developments in combining transmission electron and soft x-ray microscopy techniques, including progress in sample environment, and in situ and operando approaches and highlight the unique opportunities offered by fully correlative transmission electron and soft x-ray microscopy.

Epitaxially grown thin films are commonly used to strain engineer electronic properties by the choice of a substrate, and therefore do not match bulk properties (leading to properties that deviate from the bulk material). Free standing ultrathin oxide films are expected to preserve the bulk-like properties due to the absence of substrate influence. However,  we show that this expectation is not fulfilled with ultrathin free standing SrTiO₃, as they get ferroelectric at 80K.

A new review article, just published in Reviews of Modern Physics and highlighted on the journal cover, provides a map to the vast landscape of software codes that allow researchers to calculate Wannier functions, and to use them for materials properties predictions.  The authors, from all over Europe and the USA, include two PSI scientists. After providing readers with the theoretical foundations on Wannier functions and their calculation, together with intuitive graphical schematics to explain what Wannier functions are, the authors map the existing Wannier codes and the key applications.

In a new article published in Computer Physics Communications, the team of the Open Software Services for Classrooms and Research project (OSSCAR) describes how to create custom widgets and extensions that can be used in interactive notebooks to teach computational materials science. The article also introduces two new entries in OSSCAR: a widget to display an interactive periodic table that allows users to group elements into different states, and one to plot and visualize electronic band structures and density of states.

We solve and elucidate the physics of quantum Heisenberg  spins glasses, which governs the local moments in randomly doped, strongly correlated materials.

A group of researchers from the LMS lab at PSI has conducted a "hero run" on the new Swiss supercomputer, occupying it entirely for about 20 hours with calculations managed remotely by the AiiDA software tools. The run demonstrated the efficiency and stability of AiiDA, that could seamlessly fill the entire capacity of an exascale machine, as well as the performance of the Alps supercomputer, that has been just inaugurated. All the results will soon be published on the Materials Cloud.

Artificial intelligence (AI) is accelerating the development of new materials. A prerequisite for AI in materials research is large-scale use and exchange of data on materials, which is facilitated by a broad international standard. A major international collaboration including researchers from the LMS laboratory now presents an extended version of the OPTIMADE standard.