Finding solutions that respect the environment and whose development would open up new fields of less energy-intensive uses is vital in the ever-increasing effort to regulate polluting emissions and reduce greenhouse gas emissions. The LEDVAN project, whose major goal is to establish the viability of a new generation of Light Emitting Diodes (LEDs) based on vanadates in a manner compatible with CMOS technology to enable industrial development, fits into this scenario. This project is based on the transparency and conduction characteristics of the perovskite structure SrVO3+x as well as the emission characteristics of Sr2V2O7. In order to create a next-generation LED and lessen reliance on Ga-based LEDs, whose prices vary greatly because to the strong demand, it seeks to explore and optimize the structural, optical, and electrical features of these thin-film vanadate-based films. The production of new light sources is an important issue with a market of more than $100 billion within 5 to 10 years.

The LISBON applied research project proposed herein aims at advancing the knowledge of sulfide materials with complex crystal structures as efficient thermoelectric materials for the generation of electricity from waste heat generated by industries, road transport, data centers, and others, at a medium temperature range. The scientific approach is based on the investigation of bulk sulfide materials that contain cations with electron lone pair (such as Sb3+, Bi3+, or even Te4+ ions) to take advantage of both a complex crystal structure and the rattling effect to suppress the lattice thermal conductivity. The methodology includes synthesis, powder processing, sintering techniques, structure and microstructure analyses, transport properties measurements, and theoretical calculations. The LISBON project has as main objective to synthesize natural sulfide minerals which usually require high energy (temperatures and pressures) to form, by using original synthesis ways such as hydro/solvothermal or even high-energy ball-milling processes. Those synthesis ways might produce single crystal or nano-crystalline powder materials, which are perfectly suitable for performing cutting-edge structural characterizations such as Pair-Distribution-Function to the CRISMAT lab. The LISBON project requires a Ph.D. student to synthesize materials and to use complementary structural characterization techniques (Pair Distribution Function, Transmission Electron Microscopy, and Neutron Diffraction) to describe, not only the crystal structure of one-unit cell but the crystallographic arrangement of multiple cells. Those “big-box” structural characterizations shall give us useful information regarding the structure-property relationship.

This project is focused on thermoelectric materials with potential industrial applications at very high temperature, from 600°C to 1000°C and possibly higher, to harvest waste heat and convert it into usable energy. This particular temperature range targets the steel, non-ferrous, ceramics and glass industries that use a lot of energy, 50% of which being lost during the production process. this project will target the research and development of high temperature stable thermoelectric materials based on the cubic structure Th3P4. In this family of intermetallics, n-type La3Te4-x are already known as good thermoelectric materials with ZT above the unity above 1000°C. This project therefore proposes to develop a p-type counterpart of the same structure type, e.g rare-earth antimonides crystallizing in the anti-Th3P4 structure, making it easier to fabricate p-n thermoelectric couples. However, there is only scarce information about the p-type counterparts, even if a few reports have shown very promising thermoelectric properties and stability at high temperature, for instance a ZT of 0.75 was reported in La0.5Yb3.5Sb3 at 1000°C. These materials, their optimization (using modeling tools) and their implementation within a thermoelectric uni-couple and the subsequent demonstrator tests and qualifications are the focus of this proposal. The materials will be made via mechanical alloying followed by annealing and spark plasma sintering. These particular techniques have already proven that they allow the control of whole process, thus assuring the reproducibility of the obtained thermoelectric properties. With the development of powerful methods to compute the electronic band structure of solids and the increasing complexity of the formulations of advanced thermoelectric materials such as those targeted in this project, quantum chemical calculations based on density functional theory (DFT) will be used for the optimization of thermoelectric material properties. DFT programs embedding the most advanced approximation of the exchange-correlation functionals and taking into account relativistic effects will be employed to calculate the electronic structures required to use band engineering approach for the optimization of the thermoelectric properties of the studied materials. The third step of the project will focus on the making of the TE legs, namely, the active materials contacted on both side by metallic electrodes. This will be achieved using the LINK facilities and equipment and will be fed by the data available on the n type material (La4Te3-x) developed by NASA-JPL. CRISMAT will participate in the making of the metallized legs, metallographic studies will be performed on the different bondings and transport properties will be monitored upon ageing of the assemblies. Finally, the last challenge will be to actually build a thermoelectric converter. In essence, it consists of several unicouples connected electrically in series to form a module. The power delivered by such device obviously depends on the number of unicouples. In order to keep the project realistic and in order to be able to respond quickly to necessary design modification, small demonstrators will be privileged over large units. Besides characterization of the TE modules, these tests would serve to anticipate the applicability of the modules in industrial conditions, and anticipate potential modifications to the original design. The efficiency and durability of the module, will be used to estimate how much energy can be recovered and the economic advantage for an industrial application. Data will serve to identify other potential application domains for the modules, according to industrial process characteristics. The consortium ideally combines the expertise of well know research center, CRISMAT laboratory, IRSN Rennes, NIMS Tsukuba via the UMI LINK, and an end user: St Gobain via the CREE research center and also via its belonging to the LINK UMI

Spintronics devices involve ferromagnetic elements with high switching energies. Contrastingly, the polarization of ferroelectrics can be easily switched by an electric field, at energies typically 1000 times lower. Combined with high spin-orbit coupling elements, ferroelectrics have also a natural potential to generate a strong Rashba effect, which could allow obtaining an electrically-switchable, highly efficient spin-charge interconversion. The CONTRABASS project gathers five partners with complementary expertise in metal spin-orbitronics, oxide spintronics and spin-resolved photoemission, with the aim to demonstrate the ferroelectric control of the charge-spin conversion in Rashba heterostructures, and to explore its potential for applications. Two partners have recently obtained very important preliminary results, demonstrating the ferroelectric control of the conversion in a Al/STO 2D electron gas (2DEG) at low temperature. The conversion rate is perfectly remanent at zero field, and can be modulated in sign and amplitude up to ±60 nm, which is two order of magnitudes larger than what can be obtained in heavy metals. At the fundamental level, the ambition of CONTRABASS is to merge the fields of ferroelectricity and spin-orbitronics, and thus to reveal novel states of matter arising from the entanglement of several degrees of freedom (charge, spin, orbital and lattice). CONTRABASS has the potential to impact the fields of spintronics, ferroelectricity, multiferroism, oxide electronics and quantum materials. In particular, in spintronics the CONTRABASS project will allow replacing the ferromagnetism by ferroelectricity as the source of remanence, thus pushing the frontiers of knowledge towards directions which will fuel technology in the longer term. At the cross-road between spintronics, ferroelectricity and quantum materials physics, CONTRABASS will thus pioneer a new realm in spintronics, where spin currents can be generated, manipulated and converted by electric fields in a non-volatile way.

The aim of the PolyNASH project is to develop the growth and study of functional oxides on low-cost substrates; and to propose a new solution for the integration of complex oxides with multifunctional properties for large surface electronics. Indeed, the miniaturization of the electronic elements arrives at a limit and new solutions are sought in order to increase the integration of new functionalities (the approach "More than Moore"). Complex oxides materials offer properties such as superconductivity, ferromagnetism, ferroelectricity, multiferroism, etc., which are not present in semiconductors and are thus very promising for the development of a new generation of materials in microelectronics, Oxide-based electronics: "oxitronics". One of the difficulty of development of oxitronic devices by start-ups or industries, is the fabrication cost from substrates to device. In this project, we will implement two approaches to develop these low-cost substrates: 1 / Growth on Combinatorial Substrate Epitaxy (CSE) 2 / Epitaxy on 2 dimensional nanosheet seed layers (2D-NS). These two types of substrates have the advantage of being synthesized for a wide range of functional oxides family and to offer an alternative to the relatively expensive single-crystalline substrates which offer a limited choice of materials and crystallographic orientations. This is particularly important in order to exploit the functional properties of complex oxides, whose anisotropies (magnetism, ferroelectricity, etc.) are typically related to their crystalline orientation. In the case of CSEs, all possible orientations can be obtained in a single sample and thus make it possible to study, with a single deposition, numerous experiments carried out on single-crystalline commercial substrates. Thus, for each material, we can study and isolate the best orientation- property relationships and consequently transfer them to other types of substrates such as 2D-NS. These nanosheets are 2-dimensional materials of molecular thickness and have comparatively infinite planar dimensions. These oxide nanosheets are exceptionally rich in structural diversity that can be used as seed layers to induce epitaxy of complex oxides. Moreover, these 2D-NS have the characteristic of being able to be deposited on all types of support without any surface limitation, such as silicon. Thus, this project aims to demonstrate the potential of these two types of substrates on different families of complex oxides: perovskite, garnet and illmenite for their magnetism and multifunctional properties which are studied among others for spintronics. The project is organized in such a way that the two materials are optimized and studied in parallel and proposes a transfer of the CSE to the 2D-NS. This consortium encompasses the full range of skills required to carry out the project, which includes experts in the field of growth of the two types of substrates: the CRISMAT of Caen (CSE) and the ISCR of Rennes (2D-NS). Complex oxides will be deposited on CSE by pulsed laser ablation by the various partners that are experts in perovskite growth (CRISMAT) and garnet and ilmenite growth (GEMaC), respectively. The integration of complex oxides over large surfaces will be carried out by Atomique Layer Deposition at GEMaC and Chemical Solution Deposition at ISCR. The characterization of the thin films will be carried out structurally at CRISMAT and at the ISCR, and the physical characterizations macroscopically at the CRISMAT and on the local scale at the GEMaC. The development of these substrates will enable the study of the growth of complex oxides and their integration on universal substrates with a large surface area. This will enable the development of a breakthrough technology in the field of silicon-based devices.