Event Details

Research on antiferromagnets with special symmetries is the most rapidly developing field in magnetism and antiferromagnetic spintronics is one of the most exciting developments in condensed matter physics. The PT symmetric antiferromagnets comprise a large part of all possible systems but entail unique features, such as the current induced switching using staggered Néel spin-orbit torques. Uniquely such systems can also entail parity violation in the band structure meaning E(k) is unequal E(-k). Parity is a key property in solid-state materials and is prevalent in most of the highly active areas of research – topological insulators, unconventional superconductors, Rashba systems, centrosymmetric magnets, and others. All these materials have band structure parity due to symmetry considerations. The violation of this parity is very rare and unique in metallic systems that are Kramers degenerate, which these PT antiferromagnets are. The recent prediction that antiferromagnets, which preserve the combined symmetry of spatial parity and time – having broken both individually – can strongly violate band structure parity, came as a surprise to the community. Here we demonstrate the first direct observation of antiferromagnetic parity violation in the collinear antiferromagnet Mn₂Au by time-of-flight momentum microscopy combined with sub-micrometer spatial resolution. The spatial resolution allows uniquely to measure the band structure within a single antiferromagnetic Néel vector domain. Exploiting this new observation, we can then turn this technique as the only direct imaging tool of the Néel vector direction (not just its orientation) applicable to metallic antiferromagnetic systems.