Abstract

Transition metal oxides often having a perovskite structure form a wide and technologically important class of compounds. In these systems, ferroelectric, ferromagnetic, ferroelastic, or even orbital and charge orderings can develop and eventually coexist. These orderings can be tuned by external electric, magnetic, or stress field, and the cross-couplings between them enable important multifunctional properties, such as piezoelectricity, magneto-electricity, or magneto-elasticity. Here, will illustrate with different examples of utilization of oxide films. First, by growing PrVO₃ thin films epitaxially on an SrTiO₃ substrate, I will show that the role of oxygen vacancies can be rationalized to introduce a chemical strain similar to the so-called mechanical strain (±2%), which in turns produce a nontrivial evolution of Néel temperature in a range of 30 K. I will also present the effect of thickness, and other substrates. Second, I will show that they can also be used as bio-adaptive surfaces, a field of research which is clearly unexplored. For this, we prepared a series of oxide thin films by the pulsed laser deposition technique, grown mesenchymal stem cells on these surfaces, and studied their adhesion and proliferation. We will discuss the feasibility of different thin films to promote appearance of multicellular structures with a better performance in terms of cell proliferation. These results will confirm the potential of such materials for various applications in electronic or medicine.

Financial support from ANR and Region Normandie (INCOX project) are acknowledged.

E-mail for corresponding author: wilfrid.prellier@cnrs.fr

Abstract

Si photonics is a hybrid technology combining semiconductor logic with fast broadband optical communications and optical information technologies. With the increasing bandwidth requirement in computing and signal processing, the inherent limitations in metallic interconnects are seriously threatening the future of traditional IC industry. Silicon photonics can provide a low-cost approach to overcome the bottleneck of the high data rate transmission by replacing the original electronic integrated circuits with photonic integrated circuits. The range of emergent applications of this technology includes intra-chip data transmission, neuromorphic logic optical chips and photonic integrated circuits for quantum computing. The development has proceeded along several avenues including mounting optical devices based on III-V semiconductors and/or LiNbO₃ (LNO) on Si chips, incorporation of active optical impurities into Si, and utilization of stimulated Raman scattering in Si. All these approaches have had limited success. Recently, another path to Si photonics through epitaxial integration of transition metal oxide films was demonstrated when an effective electro-optic (Pockels) coefficient of BaTiO₃ (BTO) films epitaxially grown on Si via an SrTiO₃ buffer was reported to be an order of magnitudelarger than that in commercially-available LNO modulators. More generally, epitaxial growth of SrTiO₃ on Si(001) enables monolithic integration of many functional perovskite oxides on Si, including ferroelectric BTO, ferromagnetic LaCoO₃, photocatalytic TiO₂ and CoO, and many others.

In this talk, I will focus on two materials systems integrated on Si (001) and well-suited for implementation in the next-generation optical technologies: SrTiO₃/LaAlO₃ quantum wells and Pockels-active BTO thin film heterostructures. Both materials systems are promising for use in a wide variety of optical and electro-optical devices central to integrated photonic technologies, including quantum cascade lasers, photodetectors, electro-optic modulators and switches. The resulting devices achieve refractive index tuning with power consumption many orders of magnitude less than previously reported. Taken together, these two approached will hopefully open the door for the development of new kinds of optical and electro-optical devices for use in integrated photonics technologies.

Program

KIM Changyoung (Seoul National University)

Electronic structure studies of SrRuO₃ films in the ultrathin limit-spin structures and topological features

KIM Bongjae (Kunsan National University)

Mimicking superconductivity of Sr₂ RuO₄ using SrRuO₃ -SrTiO₃ superlattice

CHOI Woo Seok (Sungkyunkwan University)

Phase Instability amid Dimensional Crossover in Artificial Oxide Crystal

LEE Shinbuhm (DGIST)

Oxygen-vacancy-endurable conductors with enhanced transparency using correlated 4d2 SrMoO₃ thin films

PARK Sungkyun (Pusan National University)

Correlation between symmetry and phase transition temperature of VO₂

CHOI Minseok (Inha University)

First-principles investigation of strain and oxygen vacancy formation in titanates

GO Ara (Chonnam National University)

Enhanced Hund's metallicity by van Hove singularity in three-band systems

HAN Myungjoon (KAIST)

Understanding the superconductivity in infinite-layer nickelate: 2B(band) or not 2B(band)?