The Q-MAT center within the CESAM research unit focusses on quantum materials and their properties, covering both experimental and theoretical solid state physics and materials science. All matter is quantum, but specific effects and properties are only possible thanks to the exotic behavior of atoms and electrons at very small length and time scales : superconductivity, the step-wise electrical conduction of very thin wires, magnetism, and the changing chemical and optical properties of nano-sized particles are all manifestation of quantum mechanics at work.
Q-MAT comprises 6 research teams, whose PIs are presented below.
- Dr Eric Bousquet (Theoretical Materials Physics - PHYTHEMA)
Our main research objectives are to understand and design new magnetic multifunctional materials using first- and second-principles methods. The team combines the of development of new theoretical methods for magnetism with density functional theory (DFT), to model technologically appealing exotic material properties. We have added new capabilities to the ABINIT code such as finite magnetic fields, or density functional perturbation theory (DFPT) extensions to handle magnetic and magnetoelectric responses. Applications go from fundamental research (ferrotoroidal order, magnetoelectric monopoles, etc) to optimal functional materials for technological applications (sensors, spintronic, computer memories, etc). The main classes of systems are Ferroelectric and multiferroic, Magnetoelectric, and Non-collinear magnetic materials. New phenomena also appear at the interface between the aforementioned systems.
- Prof. Philippe Ghosez (Theoretical Materials Physics - PHYTHEMA)
The Group of Philippe Ghosez is active in the atomic-scale theory and modeling of the properties of materials, using first-principles techniques based on density functional theory. Our combined scientific interests are to reveal materials properties at the atomic scale, elucidate their microscopic origin and exploit the acquired knowledge to realize the rational design of bulk compounds and artificial nanostructures with optimized functional properties for applications in Electronics, Spintronics, Oxitronics and Energy. The activity is centered on various phenomena (dielectric screening, ferroelectricity, piezoelectricity, magnetism, multiferroism, thermoelectricity, structural phase transitions) in different classes of compounds (oxides, chlorites, fluorites, semiconductors, intermetallics, polymers). A special emphasis is placed on the emergence of new exotic phenomena in oxides.
- Prof. Duy Nguyen (Solid State Physics Interfaces and Nanostructures - SPIN)
The research topics developed in Professor Nguyen's team revolve around the physics of semiconductor materials, with a particular interest to the electrical, optical and magnetic properties at the interfaces in junction heterostructures and in hybrid systems, as well as the effects of low dimensionality on those properties in nanostructures. Key experimental facilities include notably a multipurpose system for the physical deposition of thin films embedded in a nanofabrication platform, an electrical characterization probestation and an infrared/visible spectrometer for photoluminescence et photoconductivity measurements. Current projects under investigation by the lab include p-type transparent semiconductors, group-IV semiconductor-based diluted magnetic alloys, conductive nanowire networks and confinement effects in toroidal nanostructures.
- Dr Jean-Yves Raty (Solid State Physics Interfaces and Nanostructures - SPIN)
In the recent years, we have used molecular dynamics and density functional theory to model various systems, mostly metals and semiconductors in different forms. Liquids, under high pressure or in confinement, amorphous systems and nanostructures are still investigated with special focus on the links between the structure and the electronic, vibrational and optical properties. Among the systems investigated, liquid alkali at high pressure and phase change materials have shown original properties. In particular, we study the link between the nature of bonding in phase change materials and the evolution of electronic conductivity in PCMs memories. In addition to this theoretical approach, we regularly perform x-ray and neutron elastic and inelastic scattering experiments, as well as x-ray absorption spectroscopy measurements at large scale experimental facilities.
- Prof Alejandro Silhanek (Experimental Physics of Nanostructured materials - MATE)
Professor Silhanek has co-authored over 150 publications in diverse topics including nanostructured superconducting, metallic, semiconducting, and magnetic systems, planar plasmonic metamaterials, biomicrofluidics devices, heavy-fermions, and quantum-critical points. Silhanek’s group is active in the domain of low dimensional systems including magnetic and superconducting materials and hybrid structures. The main experimental facilities include a platform for nanofabrication by electron beam lithography, with a multipurpose physical deposition system, magneto-optical technique and electrical transport properties of materials at low temperatures. Topics of current interest are fluctuations in low dimensional superconductors, controlled electromigration, manipulation of flux quanta, and thermomagnetic instabilities in superconductors.
- Prof Matthieu Verstraete (NANOMAT)
The group of Matthieu Verstraete revolves around the coupling of electrons and vibrations (phonons) in matter, and its consequences for transport, spectroscopy, or phase transitions. A major application is the development of materials for Thermoelectricity, converting heat into electrical current through the Seebeck effect. More generally we explore all forms of heat, charge, and spin transport in condensed matter systems, both bulk 3D (PbTe, SnSe, oxides, III-V and II-VI semiconductors, as well as metals) and nanostructured 1D (nanowires and nanotubes) and 2D materials (graphene, transition metal dichalcogenides…). A natural extension is to real time electron and ion dynamics, e.g. for molecules in very fast laser pulses. The aim is two-fold: to attain a quantitative description of materials properties, including defects, finite temperature, and a realistic environment; and to expand our understanding of complex and counterintuitive physical phenomena in condensed matter, discovering new interactions and explaining their microscopic mechanisms.
- Dr Bertrand Dupé (NANOMAT)
His research questions the links between topology and condensed matter Physics. In particular, he explores complexes magnetic states such as spin-spirals or skyrmions and their interactions with functional materials such as metals, multiferroics and superconductors.