The interaction of light and magnetism at the nanoscale is a topic of fundamental interest and with potential impact to future spintronics applications. in this work we address theoretically and experimentally the effect of femtosecond laser pulse excitation on the magnetic, structural, and chemical stability of individual magnetic cobalt nanoparticles including the role of the substrate or matrix. Eventually, we discuss possible pathways to achieve laser-induced magnetic switching in individual nanostructures.
This work has been highlighted as "Editors' Suggestion" in Physical Review B.
During the past decade, scientists have put high effort to achieve sub-10 nm resolution in X-ray microscopy. Recent developments in high-resolution lithography-based diffractive optics, combined with the extreme stability and precision of the PolLux and HERMES scanning X-ray microscopes, resulted now in a so far unreached resolution of seven nanometers in scanning soft X-ray microscopy. Utilizing this highly precise microscopy technique with the X-ray magnetic circular dichroism effect, dimensionality effects in an ensemble of interacting magnetic nanoparticles can be revealed.
X-rays and neutrons has been used to investigate the correlation between structural and magnetic chirality in magnetic fields and its impact on the polarization in multiferroic langasites. A long wavelength modulation of the magnetic structure has been found, and it is shown that the chirality of the crystals structure connects to chirality of the magnetic structure that leads to an additional electric polarization in this field induced phase, which, depending on the christal chirality, can either increase the electric polarization or lead to a reversal of it for increasing magnetic fields. The theoretical description based on allowed Lifshitz invariants intriguingly contain all the essential ingredients for the realization of topologically stable antiferromagnetic skyrmions.
A research team centered at the X-Treme beam line at the Swiss Light Source has demonstrated that spin-phonon coupling plays a major role in enhancing the magnetic stability of so-called lanthanide phthalocyanine double decker single-molecule magnets. This understanding is important in order to employ such molecules in future spintronics applications.
Via femtosecond x-ray diffraction, we observe an ultrafast increase of the octahedral rotation angle in the perovskite EuTiO3 after ultrafast laser excitation. This is opposite to what is expected from an increase in temperature. We ascribe this increase to an effective change of ionic sizes that transforms directly into a change of the Goldschmidt tolerance factor. Rotating oxygen octahedra at will opens up the possibility to control electronic and magnetic properties of perovskites on ultrafast timescales.
SIM beamline scientist Carlos Vaz was recognized as outstanding referee for providing high quality peer review for the Journal of Materials Chemistry C (Royal Society of Chemistry).
Direct manipulation of the atomic lattice using intense long-wavelength laser pulses has become a viable approach to create new states of matter in complex materials. Conventionally, a high-frequency vibrational mode is driven resonantly by a mid-infrared laser pulse and the lattice structure is modified through indirect coupling of this infrared-active phonon to other, lower-frequency lattice modulations.
In the week of April 1-5 PSI welcomes 20 PhD students and postdocs taking part in the European HERCULES 2019 school on Neutron and Synchrotron Radiation. They will attend lectures and perform two days of practical courses at several beam lines of the Swiss Light Source.
The Einstein–de Haas effect, first demonstrated more than a century ago, provides an intriguing link between magnetism and rotation in ferromagnetic materials. An international team led by ETH physicist Steven Johnson now established that the effect has also a central role in ultrafast processes that happen at the sub-picosecond timescale — and thus deliver fresh insight into materials that might form the basis for novel devices.