The crystal Hall effect and topological spintronics in antiferromagnets
Beyond! Distinguished Lecture
- Date: Aug 9, 2019
- Time: 02:00 PM (Local Time Germany)
- Speaker: Prof. Dr. Jairo Sinova
- University of Mainz
- Location: Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle (Saale)
- Room: Lecture Hall, B.1.11
The
effective manipulation of antiferromagnets (AF), through the recently
proposed and discovered Néel spin-orbit torque, has turned
AFM into active elements of spintronic devices. This, coupled with the
inherent topological properties of their band-structure, makes
topological antiferromagnetic spintronics a fruitful area of
exploration. A key remaining challenging aspect is the observation
of the Néel order parameter. Here we show that the anomalous Hall
effect can play a key role, which over a century, continue to play a
central role in condensed matter research for their intriguing
quantum-mechanical, relativistic, and topological nature.
Here we introduce a microscopic mechanism whose key component is an
asymmetric spin-orbit coupling originating from lowered symmetry
positions of atoms in the crystal. Based on first-principles
calculations, we demonstrate a pristine form of this crystal Hall
effect in a room-temperature rutile antiferromagnet RuO2 whose Hall
conductivity reaches 1000 S/cm. While a collinear antiferromagnetic
order of magnetic moments alone would generate zero Hall response, the
effect arises when combining it with the spin-orbit
coupling due to non-magnetic atoms occupying non-centrosymmetric
crystal positions. The crystal Hall effect can also explain recent
measurements in a chiral antiferromagnet CoNb3S6, and we predict it in a
broad family of collinear antiferromagnets.