The design and investigation of magnetic topological candidates under high pressure and chemical doping conditions

After the discovery of the first intrinsic antiferromagnetic topological insulator, MnBi2Te4, the search for novel bulk magnetic topological materials and their structural families has captivated both experimentalists and theorists in the condensed matter community. With the incorporation of magnetism into topological materials, a myriad of diverse nontrivial phenomena has been realized such as axion electrodynamics, the quantum anomalous Hall effect (QAHE), and Majorana fermions. Furthermore, an interplay between the magnetism and topological states can be achieved providing a source of control over these materials. If technologically realized, magnetic topological materials would be highly beneficial having a wide range of applications some of which include thermoelectrics, photovoltaics and even quantum computation.There are several key design principles to considering for intrinsic magnetic topological materials including spin orbit coupling, crystal symmetry and dimensionality as well as charge balance concepts. Various structural motifs have already been uncovered, promoting the future prediction and discovery of these materials. There are several ways in which magnetic topological materials can be tuned. Here we will discuss chemical doping and high-pressure techniques. Chemical doping was chosen due to the benefits of having a relatively low cost and simple fabrication process, which could be performed via high-temperature solid state reactions, while being able to track very subtle changes of both the structure and physical properties. To externally tune the materials, high-pressure was utilized, which is advantageous for manipulating the chemical bonding environment of materials and accessing new platforms hosting topological states that may not be possible at ambient pressure. Recent advances in the new Zintl phase family AM2X2 (A = Alkali, Alkaline-earth, and rare-earth elements; M = transition metals, main group metalloids, and Alkaline-earth; X = Pnictide elements) of topological candidates has motivated the work in this thesis to investigate the magnetic topological materials stemming from the archetypal Mg3Bi2 possessing the trigonal La2O3-type structure. The chemical bonding environment, magnetic behavior and topological states are explored and further tuned through chemical doping and high-pressure methods and subsequently characterized with neutron diffraction techniques.Ph.D.Includes bibliographical reference