Theory and Modelling

Theory and Modelling

Materials and Condensed Matter Physics is an exciting and rewarding area for research for fundamental and applied physics. The area is broad with many different aspects, encapsulating topics as seemingly disparate as how electrons scatter in plasmas to how financial markets collapse. Some of the most fascinating problems are found in mesoscopic systems which display quantum phenomena in carefully crafted geometries produced with state of the art nanotechnology. The challenges for theorists and computational physicists are particularly exciting, because of the vast, unexplored possibilities created by our unprecedented capabilities for manipulating matter with atomic scale precision.

Our interests and expertise include:

1) Linear and nonlinear spinwaves in confined geometries. Experimental and theoretical studies of magnetic excitations in magnetic materials. The materials are patterned (or self organised) assemblies of elements with micro- and nanometre dimensions. Some of these structures support dynamical solitons and have applications to magnetic logic, microwave signal processing devices, and spin electronic devices. Applications include magnetic logic schemes.

2) Interface physics of polarisable materials. Experimental,  theoretical and computational studies of ferroelectric, magnetic and multiferroic materials, elements and heterostructures. A central problem is how magneto-electric coupling can occur. Applications exist for spin electronic devices and data storage.

3) Frustration and ordering in complex materials. Theory and computational simulation of spin ordering in disordered and random systems. Topics include artificial spin ices, spin glasses, and exchange bias. Most of our projects are done in close collaboration with experiment.

4) Domain wall dynamics and conduction spin transport. Theoretical and computational studies of magnetic and ferroelectric domain walls in wires and two dimensional layers. Experiments are done through collaborations with other groups. These are model systems for fundamental investigations of transport in complex systems: diffusion of phase boundary walls, diffusion of spin waves, and spin dependent quantum transport of electrons.

 

5) Scattering theory for magnetic structures. This involves calculating scattering cross sections from ferro- and antiferromagnetic films and heterostructures patterned into micro- and nanometre structures. Experiments are done through collaborations with other groups. This work provides analysis tools for a variety of investigations into fundamental issues in low dimensional and interface magnetism.

Tantala model6) Atomic structure simulation in amorphous materials. Using a combination of reverse Monte Carlo modelling (moving atoms at random until they match experimental data) and Density Functional Theory (numerical approximate solutions of the Schroedinger equation for a many atom system) we can model the atomic structures of amorphous materials starting from experimental data - such as electron or X-ray scattering data, compositional measurements from spectroscopy, and density measurements from X-ray reflectometry.  This modelling is allowing us an unprecedented insight into the structure of amorphous tantalum oxides and related materials.