PHYSICAL PROPERTIES OF THE SUPERCONDUCTING, TOPOLOGICAL TERNARY CHALCOGENIDE FAMILY [Tl4](SnxTl1-x)Te3

topological Insulator;superconductor;Materials Science & Engineering

Wasser, Benjamin D.

Johns Hopkins University

关键词: topological Insulator;    superconductor;    Materials Science & Engineering;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/37099/WASSER-THESIS-2014.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

It has been recently discovered that the perovskite superconductor Tl5Te3 and its tin-doped derivative, [Tl4](Tl 0.4Sn0.6)Te3 have topologically protected metallic surface states. However, when Tl5Te3 is fully doped with tin, the system is predicted by Density Functional Theory (DFT) to be without surface states. This implies that there exists a topological transition determined by amount of tin that is doped in the system. Here we report the physical properties of the [Tl4](SnxTl1-x)Te3 family of materials. Structurally, a symmetry lowering distortion occurs when tin and thallium order on the perovskite ;;B” site, causing a loss of the 4-fold axis and tetragonal symmetry of the parent I4/mcm space group. This structural transition coincides with the loss of superconductivity around x=0.5. The large superconducting fraction of Tl5Te3, the superconducting dome, and the strong Sn composition-property coupling, make [Tl4](Tl 0.4Sn0.6)Te3an ideal platform in which to probe the topological phase transition in a superconductor.