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| Electronic Structure Group |
Overview
Our work is focused on the electronic structure of doped metal oxides and development and application of many body methods to solids.
Doped metal oxides exhibit a range of properties including colossal magnetoresistance in manganites, superconductivity in cuprates and high temperature ferromagnetism in transition metal doped zinc oxide. Our goal is to understand these and other phenomena in oxides using first principles (or ab initio) methods for calculating the electronic structure of these materials.
The magnetic ground states of these systems are determined by exchange couplings between neighbouring transition metal ions. Undoped transition metal oxides are usually anti-ferromagnetic insulators and exchange couplings are described by a superexchange mechanism. In doped transition metal oxides, holes are introduced into the O2p and metal d states. These holes may induce a ferromagnetic coupling between neighbouring metal ions known as double exchange. In some of the doped metal oxide systems we have studied, holes localise to a considerable degree on particular O ions in a polaronic configuration. We have studied the La1-xCaxMnO3 system extensively. More recently we have studied magnetite (Fe3O4), the cuprate Ca2-xNaxCuO2Cl2 and Co doped ZnO. |
Spin structure of La1-xCaxMnO3.
The orientations of magnetic moments obtained by neutron scattering are shown as arrows. Mn ions are shown as brown or green spheres and sites where holes may localise on O ions as O- are indicated by red or blue spheres. |
The goal of the EXCITON project is to develop a many-body code capable of performing GW and Bethe-Salpeter equation calculations for crystalline solids in a Gaussian orbital basis. This is an extension of the work that we do using the CRYSTAL code which is a Gaussian orbital code for Hartree-Fock and density functional calculations on solids.
For more details on these projects, click on the research link on the left.
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Postgraduate positions available
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