Electronic Structure Studies Of Ybasub 2cusub 3osub X6 2 Le X Le 6 9 Using Angle Resolved Photoemission

Author : Zhongkai Liu
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (881 download)

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Download or read book Electronic Structures of Novel Complex Materials Studied by Angle Resolved Photoemission Spectroscopy written by Zhongkai Liu and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Electronic Structure is the key factor for identifying new material or phases and understanding the underlying physics behind emergent phenomena. In the investigation of the electronic structures of novel complex materials, the angular resolved photoemission spectroscopy (ARPES) serves as a powerful tool. The thesis summarizes two of my graduate research projects, which both involves probing electronic structures and analyzing underlying physics on novel complex materials with state-of-the-art ARPES techniques: In the first part, I would summarize our investigation on the materials with non-trivial topology. I would start from our initial work on the three-dimensional topological insulators where we identified the characteristic surface states and verified that they are robust from perturbations. Following the line of search, we discovered three-dimensional topological insulators with other interesting properties, including the strongly inversion asymmetric topological insulator BiTeCl, and the strongly correlated topological Kondo insulator SmB6. We further extended our research to Na3Bi and Cd3As2, where we found them hosting a three-dimensional Dirac point and are first examples of topological Dirac semimetals, a three-dimensional analogue of graphene. In the second part of my thesis, I would discuss the ARPES study on the electron correlation level in the iron chalcogenide family Fe(Se, Te). For the parent compound FeTe, we discovered "peak-dip-hump" spectra with heavily renormalized quasiparticles in the low temperature antiferromagnetic state, characteristic of coherent polarons seen in other correlated materials. The increase of Se ratio leads to an incoherent to coherent crossover in the electronic structure. Furthermore, the reduction of the electronic correlation in Fe(Se, Te) evolves in an orbital-dependent way, where the dxy orbital is influenced most significantly. Finally, in comparison with other members of iron chalcogenides (AxFe2-ySe2, A=K, Rb, Cs; and monolayer FeSe film on SrTiO3 substrate), we found the strong correlation behavior is universal in all iron chalcogenides. Specifically, the dxy orbital is always heavily renormalized and loses spectral weight upon raising temperature. Several physical models of the orbital dependent physics and electron correlations would be discussed.