Observation of flat bands in a near room temperature van der Waals Ferromagnet

The two-dimensional (2D) van der Waals magnets has attracted much attention recently due to their tunability and versatility towards a new generation of spintronic devices. Here we present evidence from high resolution angle-resolved photoemission spectroscopy study of a near room-temperature ferromagnet Fe_5-xGeTe_2. Interestingly, we resolve a number of electronic dispersions that remain flat across a large portion of the Brillouin zone. In addition, we will present evidence for Dirac crossings that reveal the non-trivial topological properties of this material. The temperature evolution of the electronic structure across Tc will also be discussed. Overall, our observations reveal Fe_5-xGeTe₂ to be a rich material platform for understanding correlation and magnetism in the presence of non-trivial topology.