UBC Theses and Dissertations
The low energy electronic structure of Sr₃Ru₂0₇ : an ARPES and XAS study Hossain, Md. Anwar
Sr₃Ru₂O₇ has recently attracted a lot of research effort primarily due to the discovery of magnetic field tuned quantum criticality at low temperature [7, 8]. To understand the mechanism driving the system to this critical point, we need precise information on the low energy electronic excitations, electronic correlation effects and local electronic structure of the system, which are still a subject of intense debate. To address these issues we employed three powerful theoretical and experimental techniques: Density Functional Theory (DFT), Angle Resolves Photoemission Spectroscopy (ARPES) and X-Ray Absorption Spectroscopy (XAS). The band structure calculations were done using the TB-LMTO-ASA (tight binding-linear muffin tin orbital-atomic sphere approximation) approach . Our result agreed very well with the previous calculations [30, 31, 41, 42]. The Density of States (DOS) data were used to interpret the angle dependence of XAS data. We begin with an analysis of the metallic ground state and hybridization between the orbitals in Sr₂RuO₄ using the XAS data. The same line of analysis was used to interpret Sr₃Ru₂O₇ XAS data. Our data clearly shows the extra features expected due to the presence of a new oxygen site in Sr₃Ru₂O₇ with respect to Sr₂RuO₄. With ARPES we obtained the first high resolution Fermi surface of Sr₃Ru₂O₇ and quasiparticle band dispersion. The overall low energy electronic structure appears to be in agreement with the band structure calculations of Singh et. al. .
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