Symmetry, negative thermal expansion and superconductivity in layered perovskite oxides

Layered perovskite oxides exhibit a wide range of functional properties including ferroelectricity, magnetoresistance, negative thermal expansion and superconductivity.

In this talk, I will focus on Ruddlesden-Popper layered perovskites with chemical formula A2B04. I will give two examples of how an approach which combines first-principles electronic structure calculations and structural symmetry analysis with experimental characterisation is able to provide insights into the properties associated with materials in this class.

The first example is negative thermal expansion in Ca2Mn04 and Ca2Ge04; and the second is the LTO-LTT phase transition in hole-doped lanthanum cuprates, which coincides with the suppression of superconductivity in favour of the stablisation of stripe order.

Refreshments for attendees will be served in the meeting room adjacent to the lecture theatre (3:30-4pm).