News
Nanoworlds in 3-D
Tomographic images from the interior of fossils, brain cells, or computer chips are yielding new insights into the finest of structures. These 3-D images are made possible by the X-ray beams of the Swiss Light Source SLS, together with detectors and sophisticated computer algorithms developed at PSI.
Emergence of Nontrivial Low-Energy Dirac Fermions in Antiferromagnet EuCd2As2
When magnetism meets topology, colorful novel states can emerge in condensed matter. It is widely believed that parity-time symmetry plays an essential role for the formation of Dirac states in Dirac semimetals. So far, all of the experimentally identified topological nontrivial Dirac semimetals possess both parity and time reversal symmetry. Since the magnetism will break time-reversal symmetry, only in special cases the Dirac states can be protected in a magnetic system. Thus, the realization of magnetic topological Dirac materials remains a major issue in the research of topological physics. In this work, the authors ascertained that the ground state of EuCd2As2 is a good candidate for magnetic topological Dirac semimetal when the spins point in the out-of-plane direction in the A-type antiferromagnetic phase. The Dirac state is protected by the combination of parity-time symmetry with additional translation operation. Moreover, when the spins deviate from out-of-plane direction, the bulk Dirac cone will open a gap, and the system develops into a novel state containing axion insulator, antiferromagnetic topological crystalline insulator, and higher order topological insulator.
A link between quantum magnetism and electronic band topology
Muon spin rotation experiments establish a quantitative link between the magnetic and topological electronic properties of the kagome magnet Co3Sn2S2 — and demonstrate effective ways for tuning these properties.
The multi-layered physics of layered superconductors
Muon spin rotation experiments provide unique microscopic insight into the superconductivity and magnetism of transition metal dichalcogenides — and reveal complex and unconventional patterns, hinting towards a common mechanism for and electronic origin of ‘unconventional’ superconductivity.
Weyl fermions discovered in another class of materials
A particular variety of particles, the so-called Weyl fermions, had previously only been detected in certain non-magnetic materials. But now researchers at PSI have experimentally proved their existence for the first time in a specific paramagnetic material.
First demonstration of a Germanium laser
Scientist at the Paul Scherrer Institut and ETH Zürich, with colleagues from CEA Grenoble, have demonstrated and characterized a technology that, for the first time, yields lasing from strained elemental Germanium. This achievement underlines PSI’s leading role in the development of Silicon-compatible laser light sources.
First Demonstration of Sub-femtosecond X-ray Pulses at SwissFEL
We have produced ultra-short X-ray FEL pulses at SwissFEL by strongly compressing low-charge electron beams. Single-shot spectral measurements with only a single mode (see the figure below) indicate a pulse duration well below one femtosecond (detailed analysis on the exact pulse duration is ongoing).
From semiconductors to quantum technologies symposium
While information technology over the last 50 years has been based on conventional semiconductor electronics, future technologies – aiming to enhance the performance of computers, sensors and to secure data communication for the future internet – will use the quantum origins of nature.
This symposium highlighted the opportunities for the traditional semiconductor materials to remain the platform on which also the new quantum technologies will build on. The symposium, in part a celebration of the career of PSI Quantum Technologies group leader Hans Sigg, was held at ETHZ and included notable speakers both local and international, Gabriel Aeppli (PSI, ETHZ & EPFL), Jérôme Faist & Klaus Ensslin (ETHZ), Theo Rasing (RU Nijmegen), Giordano Scappucci (QuTech-TU Delft) and Klaus von Klitzing (MPI Stuttgart).
New material also reveals new quasiparticles
Researchers at PSI have investigated a novel crystalline material at the Swiss Light Source SLS that exhibits electronic properties never seen before. Among other things, they were able to detect a new type of quasiparticle: so-called Rarita-Schwinger fermions.