Dimitrios Koumoulis

NMR probe of metallic states in nanoscale topological insulators

A 125Te NMR study of bismuth telluride nanoparticles as a function of particle size revealed that the spin-lattice relaxation is enhanced below 33 nm, accompanied by a transition of NMR spectra from the single to the bimodal regime. The satellite peak features a negative Knight shift and higher relaxivity, consistent with core polarization from p-band carriers. Whereas nanocrystals follow a Korringa law in the range 140-420 K, micrometer particles do so only below 200 K. The results reveal increased metallicity of these nanoscale topological insulators in the limit of higher surface-to-volume ratios.

Understanding Bulk Defects in Topological Insulators from Nuclear‐Spin Interactions

Non-invasive local probes are needed to characterize bulk defects in binary and ternary chalcogenides. These defects contribute to the non-ideal behavior of topological insulators. We have studied bulk electronic properties via

Site‐Specific Contributions to the Band Inversion in a Topological Crystalline Insulator

^{125}

NMR study of native defects in PbSe

Te NMR in Bi

Nanoscale β-nuclear magnetic resonance depth imaging of topological insulators

_2

Two-band model interpretation of the p- to n-transition in ternary tetradymite topological insulators

Te

Effects of Cd vacancies and unconventional spin dynamics in the Dirac semimetal Cd3As2

_3

Microscopic Dynamics of Li+ in Rutile TiO2 Revealed by 8Li β-Detected Nuclear Magnetic Resonance

, Sb

Mechanical and anticorrosive properties of copper matrix micro- and nano-composite coatings

_2

A Combined NMR and DFT Study of Narrow Gap Semiconductors: The Case of PbTe

Te