Giant and reversible electronic structure evolution in a magnetic topological material EuCd2As2

The electronic structure and the physical properties of quantum materials can be significantly altered by charge carrier doping and magnetic state transition. Here we report a discovery of a giant and reversible electronic structure evolution with doping in a magnetic topological material. By performing high-resolution angle-resolved photoemission measurements on EuCd₂As₂ , we found that a huge amount of hole doping can be introduced into the sample surface due to surface absorption. The electronic structure exhibits a dramatic change with the hole doping which cannot be described by a rigid band shift. Prominent band splitting is observed at high doping which corresponds to a doping-induced magnetic transition at low temperature (below ∼15 K) from an antiferromagnetic state to a ferromagnetic state. These results have established a detailed electronic phase diagram of EuCd₂As₂ where the electronic structure and the magnetic structure change systematically and dramatically with the doping level. They further suggest that the transport, magnetic, and topological properties of EuCd₂As₂ can be greatly modified by doping. This work will stimulate further investigations to explore for new phenomena and properties in doping this magnetic topological material.