Scientific Highlights
Wir starten mit 500 Millionen Myonen
Mit Myonen lassen sich Materialien für die Elektronik der Zukunft untersuchen. Die beiden PSI-Forscher Alex Amato und Thomas Prokscha erklären im Interview die Besonderheit dieser Elementarteilchen.
Macroscopic phase separation of superconductivity and ferromagnetism in Sr0.5Ce0.5FBiS2-xSex revealed by μSR
The compound Sr0.5Ce0.5FBiS2 belongs to the intensively studied family of layered BiS2 superconductors. It attracts special attention because superconductivity at Tsc = 2.8 K was found to coexist with local-moment ferromagnetic order with a Curie temperature TC = 7.5 K. Recently it was reported that upon replacing S by Se TC drops and ferromagnetism becomes of an itinerant nature.
Signatures of the topological s+- superconducting order parameter in the type-II Weyl semimetal Td-MoTe2
In its orthorhombic Td polymorph, MoTe2 is a type-II Weyl semimetal, where the Weyl fermions emerge at the boundary between electron and hole pockets. Non-saturating magnetoresistance and superconductivity were also observed in Td-MoTe2. Understanding the superconductivity in Td-MoTe2, which was proposed to be topologically non-trivial, is of eminent interest.
Coulomb spin liquid in anion-disordered pyrochlore Tb2Hf2O7
The charge ordered structure of ions and vacancies characterizing rare-earth pyrochlore oxides serves as a model for the study of geometrically frustrated magnetism. The organization of magnetic ions into networks of corner-sharing tetrahedra gives rise to highly correlated magnetic phases with strong fluctuations, including spin liquids and spin ices. It is an open question how these ground states governed by local rules are affected by disorder.
Complementary Response of Static Spin-Stripe Order and Superconductivity to Nonmagnetic Impurities in Cuprates
We report muon-spin rotation and neutron-scattering experiments on nonmagnetic Zn impurity effects on the static spin-stripe order and superconductivity of the La214 cuprates. Remarkably, it was found that, for samples with hole doping x ≈ 1/8, the spin-stripe ordering temperature Tso decreases linearly with Zn doping y and disappears at y ≈ 4%, demonstrating a high sensitivity of static spin-stripe order to impurities within a CuO2 plane.
High-Tc superconductivity in undoped ThFeAsN
Unlike the widely studied ReFeAsO series, the newly discovered iron-based superconductor ThFeAsN exhibits a remarkably high critical temperature of 30 K, without chemical doping or external pressure. Here we investigate in detail its magnetic and superconducting properties via muon-spin rotation/relaxation and nuclear magnetic resonance techniques and show that ThFeAsN exhibits strong magnetic fluctuations, suppressed below ≈35 K, but no magnetic order.
Quantum Griffiths Phase Inside the Ferromagnetic Phase of Ni1-xVx
We study by means of bulk and local probes the d-metal alloy Ni1-xVx close to the quantum critical concentration, xc ≈ 11.6%, where the ferromagnetic transition temperature vanishes. The magnetization-field curve in the ferromagnetic phase takes an anomalous power-law form with a nonuniversal exponent that is strongly x dependent and mirrors the behavior in the paramagnetic phase.
Pressure-induced magnetic order in FeSe: A muon spin rotation study
The magnetic order induced by the pressure was studied in FeSe by means of muon spin rotation (μSR) technique.
Emergent magnetism at transition-metal-nanocarbon interfaces
Interfaces are critical in quantum physics, and therefore we must explore the potential for designer hybrid materials that profit from promising combinatory effects. In particular, the fine-tuning of spin polarization at metallo–organic interfaces opens a realm of possibilities, from the direct applications in molecular spintronics and thin-film magnetism to biomedical imaging or quantum computing.