VINSE Colloquium Series “Low-dimensional ternary transition metal chalcogenides” Dr. Zhiqiang Mao, Tulane University 02/21/18
February 21, 2018 Zhiqiang Mao Tulane University
Professor of Physics Nicholas J. Altiero Professor in Science and Engineering Department of Physics and Engineering Physics "Low-dimensional ternary transition metal chalcogenides" 4:10 PM, 5326 Stevenson Center Refreshments served at 3:45 Abstract
Individual atomically-thin layer of transition metal dichalcogenides (TMDCs) such as MoS2 and WS2 has attracted widespread attentions due to their distinct properties such as large direct band gaps and high photoresponsibility. The distinct properties of 2D TMDCs are attributed to the combined effects of quantum confinement, localized d-bands, spin-orbital coupling, and inversion symmetry breaking. In general, these parameters can have greater tunability in ternary transition metal compounds (TTMCs), which is our research focus. Therefore, 2D TTMCs can reasonably be expected to exhibit distinctive properties. In this talk, I will discuss our recent progresses in the study of 2D TTMCs. I will show several new 1D/2D TTMCs discovered through our efforts, including Nb3SiTe6, Ta2(Pt/Pd)3Se8, and ZrSi(Se/Te). All these materials exhibit interesting properties. 2D Nb3SiTe6 exhibits quantum transport properties, i.e., weak antilocalization (WAL). Through the study of thickness dependence of WAL, we demonstrated a long-standing theoretical prediction–electron-phonon interaction is suppressed in the low-dimension limit [1]. 1D Ta2(Pt/Pd)3Se8 nanowires show semiconducting properties and transistor performance in the FET devices [2]. For ZrSi(Se/Te), we have shown they host a new topological state, i.e., the Dirac nodal line state [3]. In the transport measurements on their 2D nanoflakes, we have observed signatures of topological surface states.
References:
[1] Hu et al., Nature Physics 11, 471 (15).
[2] X. Liu et al., Nano Lett. 16, 6188 (2016).
[3] Hu et al., Physical Review Letters 117, 016602 (2016)