Description of the thesis topic

Spintronic and Optoelectronic Devices in Hybrid Two-Dimensional Heterostructures: From Spin Control to the Exploration of Collective Luminescence Regimes

Two-dimensional (2D) materials, particularly transition metal dichalcogenides (TMDCs) and hexagonal boron nitride (hBN), have profoundly transformed materials physics and optoelectronics since their emergence. Their atomically thin thickness, strong spin-orbit coupling, lack of inversion symmetry, and compatibility with van der Waals heterostructure stacking make them highly attractive platforms for studying novel electronic, optical, and spintronic properties.

These features have led to the emergence of a new class of artificial materials with tunable properties, opening the way to a wide range of applications in electronics, optoelectronics, and quantum information. At the same time, defect engineering in these materials is experiencing rapid development, with promising applications in sensing, quantum cryptography, and quantum optics in general.

In this context, the development of new spintronic, valleytronic (using spin or valley as degrees of freedom to carry information), and optical devices based on 2D structures is built on three main research axes :
(i) A detailed understanding of the intrinsic spin-optoelectronic properties of the materials;
(ii) The study of interaction mechanisms between layers in innovative heterostructures;
(iii) The exploration of the photophysical properties of individual defects and how they are modified when organized into dense arrays. This latter aspect, still largely unexplored in semiconductors, opens the possibility of observing exotic collective phenomena such as superfluorescence.

This PhD project aims to contribute to the exploration of these three axes, focusing on the study of advanced heterostructures composed either exclusively of TMDCs or of hybrid structures incorporating magnetic layers, chiral molecules, or chiral perovskites. One of the initial objectives will be to refine the fabrication techniques for high-quality van der Waals heterostructures. These structures will then serve as the foundation for studying electronic, spin, and light-matter interaction properties. In parallel, we will investigate collective effects such as superfluorescence in geometrically controlled arrays of optical emitters (defects in hBN), to assess their potential for coherent control of light emission.

All these investigations will rely on advanced optical spectroscopy techniques, including multidimensional approaches (spatially, energetically, polarization- and time-resolved), combined with high-precision nanofabrication capabilities.

Available equipment and facilities:

Complete optical spectroscopy platforms, with spatial, temporal, and polarization resolution, for the analysis of optical and spin properties of heterostructures, including transport and scattering;

Access to state-of-the-art facilities for fabricating 2D-material-based devices (“Exfolab” platform at LPCNO and “AIME” at INSA Toulouse).

Work Context

Studying the exciting properties of nano-objects is a thriving research field at the crossroads of solid-state physics, chemistry and material science. This research has greatly evolved during the past decades for two main reasons. First, a large variety of growth techniques allow precise control of the physical properties (such as material, size and shape) and therefore the future applications of the nano-objects. Second, advances in nano-electronics and microscopy allow addressing and controlling the properties of individual nano-objects.

The goal of this ultimate miniaturization of solid-state devices is to create objects with new properties that cannot be achieved in their macroscopic counterparts. These nano-devices find application in many branches of industry such as telecommunication and information processing, transport, safety, health and environment. They also open up exciting avenues for fundamental research based on controlling individual quantum states optically or electrically.

Our research aims to study individual, self-assembled nano-objects with optimized structural quality. The systems studied include semiconductor quantum dots, magnetic nano-particles, nano-tubes, biomolecules and DNA strands. The samples are grown at the LPCNO and by our numerous national and international collaborators.

The expertise of the LPCNO covers: :
- Optical spectroscopy and semiconductor spin physics
- Nanostructuring
- Nanomagnetism
- Transport measurements
- Synthesis of nanoparticles
- Molecular modeling

More than 90 persons (researchers, lecturers, technical staff, students, post-docs) work at the LPCNO, organized in 5 research groups :

- “Nanomagnetism” group
- “Quantum Optoelectronics” group
- “Nanostructures and Organometallic Chemistry” group
- “Nanotech” group
- “Physical and chemical modeling” group