Experimental investigation of Co₂MnGa: candidate for the first intrinsic, three-dimensional topological magnet.

To date, the field of topological phases of matter has focused on band inversions driven by spin-orbit coupling (SOC). An open frontier is the search for topological invariants driven instead by magnetism. Since magnetic exchange splitting can be much larger than SOC, band inversions in magnetic systems may allow robust topological transport at room temperature. Magnetism also allows new topological phenomena. For instance, the configuration of topological objects may change with the direction of sample magnetization. Recently, we used density functional theory (DFT) to predict that the ferromagnet Co₂MnGa hosts a magnetic topological phase with a network of topological line nodes. Here we present a preliminary experimental investigation of Co₂MnGa using transport and angle-resolved photoemission spectroscopy (ARPES). We observe a robust ferromagnetic order with a high Curie temperature of ~ 700 K. Our ARPES measurements are consistent with DFT in the magnetic phase, confirming that we access the magnetic band structure in ARPES. Our findings pave the way for the discovery of the first intrinsic, three-dimensional topological magnet in Co₂MnGa.