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Title: An investigation into self assembled super-lattices of strongly correlated adatoms on metallic surfaces through the use of dynamical mean field theory
Author: Blackbourn, David James
ISNI:       0000 0004 6421 5035
Awarding Body: King's College London
Current Institution: King's College London (University of London)
Date of Award: 2017
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We use dynamical mean field theory to investigate the nature of self assembled super-lattices of strong correlated adatoms on metallic surfaces, motivated by the realisation of a Ce super-lattice on an Ag(111) surface, which invites interest as a significant step in our understanding and manipulation of complex nano-scale systems and in the development of technological applications such as atomic scale memory devices. We build upon previous tight binding studies by using the Anderson impurity model to describe a collection of one band strongly correlated impurities on a surface, which exhibit an on-site Coulomb repulsion U when doubly occupied and can hybridise with the adsorbed surface states. We set out the DMFT framework used, explaining how we employ the Hubbard 1 approximation and exact diagonalisation impurity solvers to self consistently include the strong Hubbard U interaction. We discuss the mathematical methods used in the course of our calculations and the computational techniques which make our simulations more time and memory efficient. Our results explore the effect that changing numerous model parameters such as U, total electron density and adatom separation has on several impurity quantities, including occupation, magnetic moment and effective mass/Z function. We consider spectral functions and band structures to gain insight into changes in system behaviour due to these variations. We find that the system contains many competing interactions which produce a complex array of phenomena. We conclude that our work gives insight into the behaviour of self assembled super-lattices, suggesting the inclusion of U is important for understanding the rarity of such systems. We discuss the myriad ways in which this topic should be further studied and outline the future work to be done in improving this method and applying it to diverse problems such as disorder and cluster effects such as RKKY.
Supervisor: Weber, Cedric Raphael ; Bhaseen, Miraculous Joseph Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available