Scientists observe complex tunable magnetism in a topological material

Science Daily  March 23, 2021 An international team of researchers (USA – Ames Laboratory, Iowa State University, University of Missouri Research Reactor, Oak Ridge National Laboratory, Harvard University, Canada) discovered that EuIn2As2 has collinear antiferromagnetic order where the magnetic moment direction determines either a topological-crystalline-insulator phase supporting axion electrodynamics or a higher-order-topological-insulator phase with chiral hinge states. They used neutron diffraction, symmetry analysis, and density functional theory results to demonstrate that EuIn2As2 exhibits low-symmetry helical antiferromagnetic order which makes it a stoichiometric magnetic topological-crystalline axion insulator protected by the combination of a 180∘ rotation and time-reversal symmetries: C2×T=2′. Surfaces protected […]

Newly observed phenomenon could lead to new quantum devices

MIT News  June 15, 2020 Kohn anomalies reflect a sudden change in the graph describing a change of the capability of electrons for shielding phonons. This can give rise to instabilities in the propagation of electrons through the material and can lead to many new electronic properties. A team of researchers in the US (MIT, Pennsylvania State University, Argonne National Laboratory, Oak Ridge National Laboratory, NIST, University of Maryland) predicted and observed Kohn anomaly in the topological Weyl semimetal (WSM) tantalum phosphide. It exhibits multiple topological singularities of Weyl nodes, leading to a distinct nesting condition with chiral selection, a […]