Reduced dimensionality in materials can lead to the emergence of novel properties. A particularly exciting example is the confinement of electrons to two dimensions, as 2D electron gases can exhibit intriguing phenomena such as superconductivity and charge-density waves. However, achieving such confinement typically requires sophisticated atomic-scale engineering. Recently, through a collaborative effort between theory and experiment, we discovered a new family of layered tungsten-phosphate compounds that display 2D electron gases stabilized by self-doping and antipolar distortions

In this project, we will utilize density functional theory to explore the relationship between structure and electronic properties in these compounds, with a specific focus on the dynamic stability and the electric and chemical control of the 2D electron gases, aiming to tune their properties.

Altermagnets represent a new class of antiferromagnets characterized by distinct electronic properties due to the splitting of the spin-up and spin-down electronic bands (see Figure 1). This band splitting leads to a variety of novel properties that make these materials highly promising for future spintronic applications, such as spin-charge conversion and the development of chiral magnons for magnonic devices.

The goal of this project is to investigate theoretically the altermagnetic phases that can emerge in perovskites and related materials. Magnetic members of the perovskite family typically exhibit antiferromagnetic ordering, and their natural inclination towards octahedral tilts provides an excellent platform for altermagnetism .

The discovery of superconductivity in the nickelates has led to one of the most active topics of research in condensed matter physics in the last two years (see e.g. [1]). These systems open new exciting perspectives to eventually understand the fundamentals ofunconventional superconductivity in oxides [2]. Recently, high-temperature superconductivity of up to ~80 K was discovered in the double-layer Ruddelsden-Popper nickelate La3Ni2O7 under pressure [3]. The hypothesis is that emergence of superconductivity under pressure is directly linked to the octahedral tilts present in these materials and their influence on the electronic properties of the materials respectively such as the crystal field.

En physique, comme dans la vie, un peu de frustration rend les choses intéressantes. On s’attend en général à ce qu’à température nulle, les atomes ou les molécules s’ordonnent parfaitement, formant un état fondamental unique du système. Pourtant, dans la glace, mais aussi dans des systèmes magnétiques classiques et quantiques, une compétition entre des interactions irréconciliables («frustration ») donne lieu de manière inattendue à une entropie résiduelle finie par site – un nombre exponentiel d’états fondamentaux. À température nulle, un certain désordre subsiste dans la position de certains atomes ou dans l’orientation de leurs moments magnétiques, formant un état complexe, analogue à un liquide.