Experimental evaluation and theoretical reconsideration of the putative Weyl 'Hydrogen atom' K₂Mn₃(AsO₄)₃

Weyl semi-metals offer a unique platform to study a condensed matter analogue of the relativistic massless chiral Weyl Fermion. These materials exhibit exotic physics such as an intrinsic anomalous Hall effect, a planar Hall effect, and the chiral anomaly born of the Weyl Fermion like quasi-particles which arise near topologically protected Weyl-node features in their band structure. However, often in addition to these Weyl-nodes, Weyl semi-metals host trivial electronic states which mask the desired signatures of topological physics. Therefore, there is a significant ongoing search for a so-called Weyl ‘Hydrogen-atom’ that is a material with only a single pair of Weyl nodes at the Fermi energy and no other trivial bands present. Recently, a theoretical treatment suggested the Alluaudite compound K₂Mn₃(AsO₄)₃ as a candidate Weyl Hydrogen atom whose symmetry and spin-orbit coupling combined with a predicted ferromagnetic ground state generated only a single pair of Weyl nodes and gapped all trivial states. This presentation will report on recent experimental work evaluating K₂Mn₃(AsO₄)₃ as such a candidate material and revisit the a priori calculations to better understand its actual properties and band structure as well as to suggest potential chemical routes to improve its potential as a Weyl Hydrogen atom.