Department of Materials Science & Metallurgy

Professor of Device Materials

MA University of Cambridge
PhD University of Cambridge

+44 (0)1223 334359
mb52@cam.ac.uk
www.msm.cam.ac.uk/dmg/

Thin-Film Devices and Nanoscience

My research within the Device Materials Group is built around the deposition, microfabrication and measurement of thin-film heterostructure devices. In particular we apply novel materials and advanced nanofabrication to create new types of functional device.

Multifunctional heterostructure devices

Within a thin-film multilayer or heterostructure, ultra-thin layers of materials with radically different properties (for example superconductivity and magnetism) can be placed in contact so that the interfacial coupling can begin to dominate the equilibrium properties found in the bulk. If currents are passed through such structures then the creation of non-equilibrium charge or spin states is possible and so complex functional properties can be created. Specific examples of this type of work includes studies of spin accumulation in ferromagnetic heterostructures, complex order parameter coupling in superconducting junctions containing magnetic barriers, and the exchange coupling between ferromagnets and antiferromagnets.

The best known of the metallic oxides are the high-temperature superconductors, but materials with complex electronic properties have similar crystal structures and can be grown as thin films by laser ablation. Consequently, a major research programme is the study of epitaxial oxide heterostructure devices which enable tunnelling and direct injection of carriers between materials with very different electronic properties.

Nanofabrication and materials modification

Within a heterostructure, thin-film deposition techniques enable control of layer thickness to much better than 1 nanometre. For many systems of interest, the confinement in the other dimensions is much less critical, but there are several classes of device for which high current densities need to be applied through the layers and so methods of fabricating devices with lateral dimensions of 100 nanometres or better need to be developed.

We have developed focused ion beam nano-machining within the Department as our primary technique for patterning. This technique can be used not only for imaging device and materials microstructures but also as a nanofabrication tool. As well as direct device fabrication and measurement of device properties while they are being patterned, we are developing highly localized ion implantation for materials modification.