NICOP - Exploring and Understanding Two-Dimensional Quantum States of Transition-Metal Dichalcogenides/Oxides by Using Angle-Resolved Photoemission Spectroscopy
Abstract
Project Summary/AbstractTo overcome a certain limitation of today semiconductor devices, we need to look for advanced materials w""ith novel functionalities and/or superior performance over conventional ones. In this proposal, we are interested in transition-meta"l dichalcogenides (TMDs) and oxides (TMOs) which currently attract much attention from the frontier research communities. If success"fully proven, these families of materials may later be used for creating new-generation electronics/ spintronics/ quantum computer,"" and largely improve performance of renewable-energy generator (e.g. thermoelectric generator), energy storage (e.g. battery and sup"ercapacitor); these may align with the S&T Strategic Plan in the areas of a) Power and Energy (e.g. energy storage) and b) Informati"on Dominance (e.g. topological quantum computing/information). However, to utilize their functionalities to the full capacity or to"" unveil other hidden properties, we shouldunderstand the nature of these advanced materials from the fundamental ground.Due to th""eir rich phenomena, we would like to further explore unique quantum states of TMDs and 2DEG at the surfaces of TMOs, which may open"" up new opportunities for advanced electronic/ quantum-logic devices. In this proposal, by using angle-resolved photoemission spectr""oscopy (ARPES), we are particularly interested in the following phenomena: a) topological quantum states and spin states in TMDs and"" b) nature of 2DEGs across ferroelectric transition and NEC effect in TMOs. Regarding topological quantum states, we are motivated b"y the discovery of three-dimensional topological semimetal Na3Bi and the previous studies about the large tuneable spin splitting of" a topological insulator, Bi2Se3. Recently, we performed ARPES measurement on PdTe2; the preliminary data suggests that PdTe2 could"" exhibit both topological3D Dirac crossing in bulk and large spin splitting of the topological surface state. For TMOs, wefound th"at 2DEGs at surfaces of ferroelectric Ba-doped SrTiO3 and Nb-doped KTaO3 could largely change across transition and BiFeO3 may also exhibit the so-called negative-electron compressibility (NEC) effect where the chemical potential counterintuitively becomes lower upon increasing the surface carrier density. We would like to investigate these phenomena much further both experimentally and theo"retically.Regarding our US collaborators, there are: 1) Prof. Zhi-Xun Shen at Department of Physics, Stanford University, CA. and"" 2) Dr. Sung-Kwan Mo, Beamline 10.0.1, Advanced Light Source, Lawrence Berkeley National Laboratory, CA. We hope that after finishin""g this project, we will have a better understanding the nature of electrons in two dimensions and publish these studies in high-impa""ct journal(s), such as Appl. Phys. Lett., Phys. Rev. Lett., or Nature Phys.; we will also present these works in international meeti"ngs/conferences.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 20, 2017
- Source ID
- N629091812018
Entities
People
- Worawat Meevasana
Organizations
- Office of Naval Research
- Suranaree University of Technology
- United States Navy