FOXIDUET · Functional OXides Interfaces charge Dynamics under Ultrafast Electric Transients

Periodic Report Summary 1 - FOXIDUET (Functional OXides Interfaces charge Dynamics under Ultrafast Electric Transients)

During the first period of the MC-CIG FOXIDUET project several advances have been made, both from a scientific point of view as well as for the possible impact on the PI career development. First of all, let us briefly recall the main concepts at the base of the project. The FOXIDUET project was granted in order to perform an extended investigation on the so called “polar-nonpolar” oxide interfaces, a new class of emergent hetero-structured materials, whose potential importance for electronics and applications has been steadily increasing with time since their discovery in 2004. After about 10 years, the overall interest in this class of materials is far from being in decline, as proven by the bibliographic records: the amount of attention paid by the scientific community is far from saturation, and also the overall size of the community is still rapidly growing. The contribution to the scientific debate produced during the first period of this project is significant. Four papers and two conference proceedings about the project topics have been published during the reporting period, 8 in total with explicit acknowledgement to the project financing, 4 more articles during this period. Main advances have been established in three distinct areas: (i) general understanding of the Second Harmonic Generation (SHG) spectra of oxide interfaces, with particular attention to the LaAlO3/SrTiO3 case, which can be considered the prototype material of this class, (ii) the extension of the study to different types of interfaces, whose similarities/differences can help to shed light onto the microscopic mechanisms leading to the two-dimensional (2D) electron gas in such systems, (iii) a methodological approach aimed at investigating the advantages given by SHG as a tool for monitoring the growth of epitaxial oxide films, complementary to the standard tools today available, as for instance RHEED. Regarding the first point, several SHG spectra of LaAlO3/SrTiO3, LaGaO3/SrTiO3, and NdGaO3/SrTiO3 interfaces have been measured. This investigation allowed us to obtain a model based on symmetry, selection rules, and atomic orbital overlaps. Regarding the second point, we have investigated interfaces formed by crystalline and amorphous thin films of LaAlO3/SrTiO3. The main finding here is that the electronic properties of the two-dimensional electron gas are almost independent of the doping mechanism of the quantum well. Regarding the third point, we demonstrated that SHG could be used as a monitor for epitaxial film growth and that this technique can reveal otherwise elusive in-plane inhomogeneities of electrostatic, chemical or structural nature. Finally, the career prospects of the PI have been significantly boosted by the project, as demonstrated by (i) his participation to a COST project (TN1301 IT - Sci-GENERATION) in which he was invited specifically as a winner of a MC grant, (ii) his involvement in other research projects in different areas which have widened his skills and scientific connections, (iii) the increase of the overall impact of his publication record (14 articles in total published during the first two years of the project) which is significantly enhanced, compared to the previous periods of his career.

Data: CORDIS, © European Union