The Device Update In Dreamline And Its Applications To Studies Of Topological Materials

Recent years have witness the unprecedented splendor of topological theory.Within the framework of theory,topological materials can be mainly classified into topological insulators,topological semimetals and topological superconductors,which can still be divided with its characteristics.The universe of solid is different from the real one.The abundant interactions in solids can generate many types of quasiparticles.Thus,finding particles that exist or not exist in high-energy physics is important to profoundly understand the physical mechanisms.The thesis will contain my work in system maintenance and research.At first,I will introduce the basic principles of angular-resolved photoemission spectroscopy?ARPES?,as well as the system composition in Dreamline beamline.We can detect the energy and momentum of photoelectrons to obtain its initial state and band dispersion with ARPES,which is based on the photoemission effect.I helped to update the analyzer and manipulator for higher capacity.Then,taking graphene as the example,I will introduce the basic concepts and mechanisms in topological materials.For topological insulator,its non-trivial topological invariant can generate spin-polarized surface state with the protection of time-reversal symmetry.For topological semimetal,the novel nodal point in bulk band can be protected by time-reversal,inversion or crystal symmetries.The projection of these nodal points on the surface may bring unique Fermi arcs.In the end,I will mainly focus on two important experiment,in which I joined during my master.One is the observation of three-component fermions in MoP.We precisely measured the new fermions along?-A.We obtained enough data of band structure to prove the existence of these fermion,which is due to the band crossing of a degenerated band and a non-degenerated band.The result enriched the classification of particles.The other one is the observation of nodal chain in TiB₂.We confirmed the chain structure which is composed of two linking nodal ring.The SOC can be ignored.Also,we confirmed the lantern-type Fermi surface.These work not only verify the theoretical prediction,but also enhance the understanding of topological world.