Cernov, Cristian (2021-05). Topological and Electrochemical Properties of Organometallic Tin Polymers and Tin-Substitution Diamonds. Doctoral Dissertation.
Thesis
In this thesis, I propose practical ways to incorporate tin-based polymers, cyclic tin rings, and tin-substitution diamonds into microscale electronic devices. Using spin-polarized, noncollinear magnetization, and spin-orbit coupling calculations under the density functional theory framework, I investigate the electronic and magnetic properties of alternating tin polymers, even- and odd-member tin rings, and assess the viability of tin-substitution diamonds as candidates for Josephson junctions. I show that certain tin polymers that alternate with respect to their hydrocarbon substituents have magnetic order and can be tuned electronically to close their already narrow band gap allowing for a crossing of bands at the Fermi energy. I also show these polymers exhibit high electrical conductivity and have the appropriate geometry required for topological protection. Furthermore, I investigate the difference between even and odd tin rings and show that they are wide band gap semiconductors. I create an electronic device by incorporating a 6-member tin ring between two gold leads with sulfur contacts to investigate the electronic transport properties and assess the device for spintronics applications. Finally, I show that tin-substitution diamonds at varying tin-substitution concentration are wide band gap semiconductors that are heavily influenced by the presence of tin in the crystal lattice. I show that the phonon band structure of a tin-substitution diamond with a certain concentration of tin, indicates structural stability and no shearing of the crystal lattice. I also present a Josephson junction formed by niobium-tin superconductors and the tin-substitution diamond and discuss the viability of such a device.
