With increasing miniaturization of system components in nanotechnology, interfaces between different materials are becoming ever more prominent and can ultimately dominate performance of devices. Oxide materials play a crucial role in numerous technological applications. Advanced research in recent years has therefore focused on oxide nanostructures coupled to various (e.g. metallic and oxide) substrates with the aim to create new low-dimensional hybrid materials with novel physical and chemical properties. The growing importance of these systems stems from the fact that their hybrid character and low dimensionality entail emergent phenomena and novel properties which differ significantly from those of individual constituents. These novel properties open new avenues for materials science and design with the perspective of nanotechnology applications in the fields of heterogeneous catalysis, electronic device technology including magneto-resistive and spintronic devices, gas sensors, (multi)functional coatings or corrosion inhibition, and environmental chemistry.
Theoretical modeling plays a crucial and multifaceted role in this field. First, theory is used to set up a framework of basic principles that govern the emergent phenomena in oxide nanostructures and to provide in-depth analysis of the origins of interactions in these complex systems. Moreover, reliable computational predictions of both energetic parameters (thermodynamics of phase transformations, lattice constants, phonon spectra, chemical bonding and reactivity) and electronic structure (electric potential, charge distributions and transport, local density of states, spin coupling phenomena) can often be achieved by state-of-the-art theoretical approaches. In numerous well-documented cases, theory has helped to resolve experimental ambiguities and to predict new experiments and phenomena. However, in order to further fulfill this important role, some key challenges need to be addressed that are currently hampering theoretical analysis: (1) the accuracy of the present level of theoretical description is often unsatisfactory for this class of hybrid materials, and (2) the interactions and methodological exchanges among the different communities that deal with oxide interfaces with other materials have so far been scarce or even non-existent. For example, the catalysis, fuel cell and microelectronics communities often use the same metal/metal-oxide interfaces but have separate forums for discussions and exchange of ideas.
The proposed CECAM workshop on the topic of emergent structural and electronic phenomena at interfaces of nanoscale oxides will fully address these challenges. The proposed workshop will make an important contribution to the development of this crucial field in two ways. First, by bringing together scientific communities that are dealing with oxides and oxide interfaces from different perspectives, namely: i) electronic structure at oxide/oxide interfaces; ii) surface reactions at ultrathin oxide films; and iii) microelectronic devices. Second, by elucidating limitations and highlighting advances of electronic structure methods for accurately predicting the properties of heterogeneous multi-component systems, and by identifying strategies for structural optimization of complex interfaces and surface structures. To address the crucial issues in this field the workshop will gather top experts in theoretical and experimental topics and we expect breakthrough advances to results from the discussions and interactions at the meeting. Despite the great relevance in microelectronic, spintronics, catalysis, sensors, and other fields, this topic has not so far been specifically addressed within the CECAM framework.
The workshop will promote links and the interplay among different computational approaches employed to model interface systems of increasing complexity of components and interactions. It will start with the problems related to the structural prediction of oxide ultrathin phases grown on different supports, then lead to the methods for investigating the electronic structure of complex oxide-based interfaces, to the phenomena of electron transport across these multicomponent systems, to end with the field of catalysis and corrosion, where the interplay between electron transfer and ion transport together with structural dynamics give rise to complex phenomena
The first objective of the proposed workshop is to bring together experts from different scientific communities that have a common interest in oxides and oxide interfaces, namely:
devices and microelectronics
surface reactions at ultrathin oxide films
electronic structure at oxide/oxide interfaces
The second objective of the workshop is to provide a common overview and focus on topics that are crucial for these communities:
a. Strategies for structural optimization of complex interfaces and surface structures. The performance of genetic and basin-hopping algorithms will be scrutinized as well as combined computational/experimental methods based on spectroscopy and scanning probe techniques.
b. Advances and limitations of methods for electronic structure calculations of multi-component systems. DFT-based methods applied to oxides suffer from well-known drawbacks. Although addition of exact exchange (hybrid functional) generally improves the description of oxides, the situation is not clear for heterogeneous multi component systems.
c. Approaches to model electron and ion transfer at interfaces.
The final objective of the workshop is to facilitate cross-fertilization between different fields and help to establish new collaborations between the participants. To this aim, ample time will be allowed for interactive discussion of the oral and poster contributions and scientific exchange among participants.