The Physical Properties of Materials Group
The Physical Properties of Materials Group prepares and characterizes advanced materials featuring novel structural, electric and magnetic properties. For these fundamental studies we use in-house equipment in combination with experiments at the PSI large scale facilities. Our research is focused on the study of complex transition metal oxides with highly correlated electrons, mostly in powder or single crystalline form. This class of materials is characterized by the presence of competing interactions which often results in unusual electronic and magnetic properties. Such properties are both, challenging from a fundamental point of view and interesting for applications, especially in the fields of energy technologies, data storage and advanced electronics. Read more
Unconventional Transverse Transport above and below the Magnetic Transition Temperature in Weyl Semimetal EuCd2As2
As exemplified by the growing interest in the quantum anomalous Hall effect, the research on topology as an organizing principle of quantum matter is greatly enriched from the interplay with magnetism. In this vein, we present a combined electrical and thermoelectrical transport study on the magnetic Weyl semimetal EuCd2As2. Unconventional contribution to the anomalous Hall and anomalous Nernst effects were observed both above and below the magnetic transition temperature of EuCd2As2, indicating the existence of significant Berry curvature.
Detailed understanding of charge diffusion processes in a lithium-ion battery is crucial to enable its systematic improvement. Experimental investigation of diffusion at the interface between active particles and the electrolyte is challenging but warrants investigation as it can introduce resistances that, for example, limit the charge and discharge rates. Here, we show an approach to study diffusion at interfaces using muon spin spectroscopy.
Distortion mode anomalies in bulk PrNiO3: Illustrating the potential of symmetry-adapted distortion mode analysis for the study of phase transitions
The origin of the metal-to-insulator transition (MIT) in RNiO3 perovskites with R = trivalent 4f ion has challenged the condensed matter research community for almost three decades. A drawback for progress in this direction has been the lack of studies combining physical properties and accurate structural data covering the full nickelate phase diagram. Here we focus on a small region close to the itinerant limit (R = Pr, 1.5K < T < 300K), where we investigate the gap opening and the simultaneous emergence of charge order in PrNiO3.
Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically induced WSMs is scarce. Here, using photoemission spectroscopy, we observe that the degeneracy of Bloch bands is already lifted in the paramagnetic phase of EuCd2As2. We attribute this effect to the itinerant electrons experiencing quasi-static and quasi–long-range ferromagnetic fluctuations.
Understanding and controlling the electronic structure of thin layers of quantum materials is a crucial first step towards designing heterostructures where new phases and phenomena, including the metal-insulator transition (MIT), emerge. Here, we demonstrate control of the MIT via tuning electronic bandwidth and local site environment through selection of the number of atomic layers deposited.