We believe that harnessing the multi-functionality of oxide quantum materials can overcome the fundamental limitation of the current CMOS-based information technology. Oxides can react to electrical, magnetic, thermal and mechanical stimuli, with responses in the same or in a different `sector'. In many materials, information can be stored into and retrieved from domains of one order parameter (ferro/antiferromagnetic, ferroelectric, ferroelastic) or of a combination of multiple order parameters (multiferroic). These properties could enable the construction of a new generation of ultra-fast, non-volatile memories and of electronic devices operating beyond boolean (binary) logic. Fundamental oxide physics has been one of the main pillars of condensed-matter physics for the past 100 years. Many classes of materials with exciting properties, such as high-Tc copper oxide superconductors and colossal magnetoresistance manganese oxides were discovered over the decades, but very few practical applications have been achieved.
The ultimate goal of our group is to deliver on the promises of oxide quantum materials physics, which, we believe, will be realised in epitaxial devices – thin layers of perfect oxide single crystals grown on top of a crystal template. This is the same technology employed to manufacture high-end LEDs (light-emitting diodes). We work on a broad spectrum of problems, materials and experimental techniques, from the very fundamental to the boundary of device applications.
Research goals of the Oxide Electronics Group
- To understand the fundamental underpinning of functionality in oxides by studying how different degree of freedom (charge, orbital, magnetic) self-organise at the atomic level. To this end, we perform experiments on so-called `bulk materials' , i.e., perfect oxide single crystals and polycrystalline materials grown in our lab and by collaborators.
- To grow and characterise films of oxide quantum materials epitaxially, including `sandwiches' of oxides with different functional properties, and to understand their properties, which often differ from those of the bulk analogues in fundamental ways. We employ different growth techniques, including Molecular Beam Epitaxy (MBE) and sputtering, and we obtain other samples from collaborators.
- To build prototype oxide quantum materials devices and to characterise them in operando using scattering, microscopy and spectroscopy techniques.
Experimental and computational techniques in the Oxide Electronics Group
- Elastic neutron scattering. We perform our experiments on bulk and films samples predominantly at the ISIS facility at Rutherford Appleton Laboratory.
- X-ray scattering, including resonant and non-resonant magnetic X-ray diffraction with hard and soft X-rays. We run state-of-the-art laboratory instrumentation in the Clarendon Laboratory, but we perform most of our high-end experiment at the Diamond Light source.
- Dielectric and transport measurements. One of our specialities is to perform measurements of ferroelectricity in extremely high magnetic fields (up to 65 T – a record in the UK), using the pulsed-magnetic-field facility in the Clarendon Laboratory.
- Advanced microscopy. We employ spectral microscopy at Diamond, Magnetic Force Microscopy (MFM) and the Magneto-Optical Kerr Effect to image multi-functional domains, which are the fundamental unit of information storage in oxides.
- Non-linear and ultra-fast optics Electromagnetic radiation can be used both as a probe and as an ultra-fast stimulus of oxide quantum materials. We are developing optical techniques and instrumentations from the THz to the visible range.
- Nanofabrication. We will be using electron beam lithography and other clean-room methods to design and build prototype oxide quantum materials devices.
- First-principle atomistic modelling. In collaboration with the Materials Modelling Group in the Department of Materials, we employ Density Functional Theory methods and other computational techniques to model the functional properties of oxides and to predict their behaviour in different architectures.
Listen to a podcast on multiferroics (Paolo G. Radaelli explains).