Project Description: A direct consequence of the strong localization of the electromagnetic fields around plasmonic nanoparticles (NPs) is photothermal heating. Photothermal effects are important in almost all photonic applications. They can either be beneficial and used for nanoscale thermometry and hyperthermia therapy or be detrimental by causing material deterioration and decreasing the device optical performance, which is a significant concern in sensing, imaging, and enhanced spectroscopies. Due to the large light absorption increase induced by the localized surface plasmon resonances (LSPRs), the NPs become a heat source. This results in a localized temperature increase of tens of degrees at the metal surface and in its vicinity, which can have drastic effects on the surrounding environment. Local temperature increases may also affect the nature of the plasmon-exciton coupling in hybrid metal-semiconductor nanostructures. The goal of this computational project is to develop a computational approach based on the Finite Element Method (FEM) to model the impact of such photothermal effects on the optical properties of polariton modes, named plexcitons, which are formed by the hybridization of LSP modes and exciton in hybrid metal-semiconductor systems.

Specific Requirements (if applicable): none

Project Description: When ordered in periodic arrangements, plasmonic nanoparticles exhibit enhanced optical properties that result from collective coherent interactions. These interactions can be either mediated by near-field (short scale) or through photonic cavity effects (long scale). Traditionally, squared arrays of spherical of cylindrical nanoparticles are easy to fabricate. However, more complex arrangements and geometry provide additional controls over the tailoring of the optical response of these nanostructured systems. Here, the project aims to perform computational modeling (finite element method) of the optical properties (near-field, far-field, photonic bandstructures) of periodic arrangements of gold bipyramids, forming fishscale-type of patterns to unravel the effect of order/disorder in such lattice as well as finite-size and shape effect on these optical properties.

Specific Requirements (if applicable): none

Project Description: We seek to develop a method for 3D-printing of soft matter with ultra-high resolution. This method overcomes the diffraction limit by surface plasmons and improves the resolution to sub-50 nm by assessing various types of photosensitive resins. Surface plasmons are the collective charge oscillation at metal/dielectric interface. They can be excited by a polarized optical electromagnetic field and are located at the close vicinity of plasmonic structures (e.g. metal nanoparticles) and enhances the local optical field intensity to orders of magnitudes.

Specific Requirements (if applicable): 

Project Description: Among the numerous metal oxide nanoparticles (NPs) under active investigation worldwide, zinc oxide (ZnO) NPs are of particular interest as anticancer agents. Optimal anti-cancer therapies require systematic delivery of ZnO NPs via the circulatory system, requiring that the NPs pass through multiple barriers. Despite a wide body of research, multiple challenges remain to bring ZnO NPs to the clinic. Potential liabilities include accumulation in the body and local organ toxicity.  A lack of systematic surface and physiochemical characterizations of ZnO nanoparticles has led to confusion regarding the biological responses elicited from these materials. This interdisciplinary research will combine accurate in-silico simulations, validated by in-vitro experiments, of ZnO NPs to identify the best combination of physiochemical properties yielding optimal cancer toxicity with minimal off-target effects.  Our results will provide a deeper understanding of the mechanisms underlying selective delivery, selective toxicity, controlled aggregation, and circulation time and clearance from the circulatory system. (https://doi.org/10.3390/nano10020269)

Specific Requirements (if applicable): 

Project Description: Photoresponsive cholesteric liquid crystals (P-CLC) systems have attracted considerable interest to the very promising area of soft photonics and mechanics.1 Under light irradiation, it is possible to modulate or switch the orientation of CLC molecules to achieve desired optical and mechanical properties of this system remotely and selectively. Interestingly, P-CLCs have been used to design a new form of light-sensing microswimmers presenting a change in average direction and handedness inversion of their helical trajectory upon application of a short pulse of light.2 Such microswimmers are easily prepared by introducing micrometric LC droplets into an aqueous solution of surfactant (i.e. tetradecyltrimethylammonium bromide, TTAB) and reproduce motions similar to motile living cells,4 including helical trajectories (as for sperm cells) or rotating assembly.5 Furthermore, emergent phenomena such as synchronization are expected to occur when chiral microswimmers are examined as a flock due to the field flow coupling.[6]

During this internship the objectives will be to - determine the ability of P-GMs (see Figure) to generate cholesteric liquid crystal phases as a function of the introduced P-GMs concentration. The temperature range of these phases will be determined by differential scanning calorimetry. The structural parameters of these phases (pitch and helicity) will be determined by optical microscopy and scattering measurements. - evaluate the kinetics of the structural modifications induced by an irradiation at a chosen wavelength or by a thermal back-reaction. For this purpose, the evolution over time of the absorbance spectra and/or of the texture observed from polarized optical microscopy will be measured. - establish a structure-property relationship that will enable us to draw up a picture of the structure of P- GMs that will optimize the response of the liquid crystal medium.

References:
[1] H. K. Bisoyi et al., Light-driven liquid crystalline materials: from photo-induced phase transitions and property modulations to applications, Chem. Rev. 2016, 116, 15089
[2] B. V. Hokmabad et al., Spontaneously rotating clusters of active droplets, Soft Matter, 2022, 18, 2731. doi.org/10.1039/D1SM01795K

Specific Requirements (if applicable): none

Co-funding: A monthly stipend of ~600€ will be provided in addition to the MAT-MOVE scholarship

Project Description: Graphene is a material with a monoatomic thickness, composed solely of sp2-hybridized carbons, and exhibiting extraordinary properties including a purely 2D electronic structure, zero effective mass, record electron mobility of 180,000 cm²/V/s at room temperature, electron density that can be easily modulated with an electrostatic grid, and very high mechanical strength. Since its discovery in 2004 [1], graphene has been the focus of much interest in the scientific community for its potential use in a wide range of innovative applications in nanoelectronics [2], metrology [3], optoelectronics [4], magnetometry [5] and the study of exotic superconductors [6].

The Nanomagnetism group at LPCNO studies the galvanomagnetic properties of graphene with the ultimate aim of fabricating ultra-sensitive Hall-effect magnetic sensors based on boron nitride/graphene/boron nitride(hBN) heterostructures. We recently developed a comprehensive and novel model for the detailed understanding of the operation of graphene Hall-effect sensors [7]. 

The group is now using these graphene Hall-effect sensors to measure the static and dynamic magnetic properties of nanometer-sized ferromagnetic (FM) systems. The first area concerns the measurement, particularly at cryogenic temperatures, of 2D van der Waals FM materials such as CrI3, CrBr3, Cr2Ge2Te6 or FexGeTey [8], with the perspective of producing graphene/2D FM material heterostructures [9]. The second axis concerns the detection of high-frequency magnetic excitations in ferromagnetic dots and spin-wave propagation lines. Proof-of-concept of such detection could lift the technological bottleneck on nanoscale spin-wave detection and pave the way for magnonic devices [10].

The proposed internship concerns (i) the fabrication and characterization of Hall-effect sensors, (ii) the measurement of the magnetic properties of ferromagnetic 2D materials in hBN/graphene/hBN/2D FM/hBN heterostructures, and/or the detection of ferromagnetic resonance in magnetic dots covered with a hBN/graphene/hBN heterostructure (collaboration with CEMES-CNRS Toulouse). 

References:
[1] K.S. Novoselov et al., Science, 306, 666 (2004) 
[2] F. Schwierz, Nat. Nano. 5, 487 (2010)
[3] K.S. Novoselov et al., Nature, 438, 04233 (2005)
[4] W. Zhang et al., Sci. Rep., 4, 3826 (2014)
[5] B. Shaeffer, Nat. Comm. 11, 4163, (2020)
[6] J. M. Park et al., Nature, 590, 249 (2021)
[7] L. Petit et al., Phys. Rev. App., under review (2024)
[8] C. Gong et al., Nature, 546, 265 (2017)
[9] T. Song et al., Science 360, 1214 (2018)
[10] A. Chumak et al., Nat Com. 5, 4700 (2014)

Specific Requirements (if applicable): Masters or engineering degree, specializing in physics of matter, nano-physics and nanotechnology. The student should have a definite attraction for experimentation and multidisciplinarity.

Co-funding: An monthly stipend of ~600€ will be provided in addition to the MAT-MOVE scholarship

A PhD position would be available after the internship.

Project Description: The photonic components, that is, optical components manufactured using technologies conventionally employed in microelectronics, increasingly rely on the use of optical nonlinearities [1]. Indeed, integrated optics components made from thin layers of materials (crystalline or polycrystalline) with favorable electro-optical (Pockels) properties can have their transmission/reflection response modulated in intensity or phase (spectral tunability) [1],[2], thus rendering them active and/or reconfigurable. To date, the most commonly used material for manufacturing these devices is lithium niobate [1],[3], but barium titanate (BaTiO3) appears as a promising alternative [4].

The proposed internship is part of a collaboration between the "Mixed Valence Oxides" team at CIRIMAT, specializing in materials and ceramics of BaTiO3 in particular, and the Photonics team at LAAS, whose activities focus on the study of photonic components. It follows a previous internship that enabled the fabrication of transparent thin layers of amorphous material on glass and their densification through thermal annealing.

The objective of the internship, funded by the FERMAT federation, is to study in more detail the conditions of growth and crystallization through thermal annealing of thin films (<1 μm) of BaTiO3 deposited by sputtering on various substrates (silica, silicon, and especially SrTiO3) and to assess the influence of these parameters on the obtained electro-optical characteristics.

References:
[1] A. Boes, B. Corcoran, L. Chang, J. Bowers, et A. Mitchell, « Status and Potential of Lithium Niobate on Insulator (LNOI) for Photonic Integrated Circuits », Laser Photonics Rev. 12(4), 1700256 (2018).

[2] A. Monmayrant et al., « Cavity resonator-integrated guided-mode resonance filters with on-chip electro- and thermo-optic tuning », Opt. Express 30(10), 16669 (2022).

[3] D. Zhu et al., « Integrated photonics on thin-film lithium niobate », Adv. Opt. Photonics 13(2), 242 (2021).

[4] A. Karvounis, F. Timpu, V. V. Vogler-Neuling, R. Savo, et R. Grange, « Barium Titanate Nanostructures and Thin Films for Photonics », Adv. Opt. Mater. 8(24), 2001249 (2020).

Specific Requirements (if applicable): Master's student in physics/materials science. - knowledge of materials and optoelectronics - instrumentation know-how would be a plus. - Good oral and written communication skills - Strong motivation - Ability to work independently in a team.

Co-funding: An monthly stipend of 591,51€ will be provided in addition to the MAT-MOVE scholarship.

Project Description: Energetic materials, made from highly reactive metal fuels (Al, Mg, B) and metal oxide particles (CuO, MoO3, Fe2O3, Bi2O3) of sizes around 102 – 103 nm, known as nanothermites, have many commercial and research applications. These materials release a significant amount of energy with low gas release despite their small size. Al based nanothermites, such as Al/CuO or Al/Fe2O3, are therefore explored to provide intense, controllable and efficient energy release in small packages making them valuable in a wide range of pyrotechnic applications including cutting and welding, initiation, actuation, chip destruction and propulsion. There is continuing research effort in the area of nanothermites engineering with a special focus on improving their performance, safety and industrial utility. Specifically, one objective is to lower ignition point and sintering tendency of Al, the latter being hypothesized to be the rate-limiting step in Al-based nanothermite combustion. The goal of this technological project is to explore the combination of Al with other metallic or metalloid fuels to modify the reaction pathway, thereby influencing both the ignition and the combustion processes in nanoscale energetic composites. CuO, TiB2, Zr, Al nanolayers will be deposited using Direct Current magnetron sputtering and analyzed with a set of technique (XRD, TEM, EDS, ..). Then, Differential scanning calorimetry, high-speed videography will be used in order to elucidate combustion mechanisms.

Specific Requirements (if applicable): none

Co-funding: An monthly stipend of ~650€ will be provided in addition to the MAT-MOVE scholarship.

Project Description: Energetic materials, made from highly reactive metal fuels (Al, Mg, B) and metal oxide particles (CuO, MoO3, Fe2O3, Bi2O3) of sizes around 102 – 103 nm, known as nanothermites, have many commercial and research applications. These materials release a significant amount of energy with low gas release despite their small size. Nanothermites are therefore explored to provide intense, controllable and efficient energy release in small packages making them valuable in a wide range of pyrotechnic applications including cutting and welding, initiation, actuation, chip destruction and propulsion. However, the effective deployment of such promising materials for all these applications faces a major hurdle, arising from both the enormous material design space and lack of accurate combustion models to provide reliable design guidelines to experimental groups and engineers. Not only the chemistries (nature of fuel and oxidizer) but also the microscopic (size of the fuel and oxidizer particles, purity of the metal) and mesoscopic properties (powder density, stoichiometric conditions, binder or additives) influence the macroscopic combustion and thus the energetic performance. The aim of the project is to develop a realistic description of the self-propagating combustion front in Al based thermites, CFD models to predict the fast combustion and understand the dynamics of the flame.

Specific Requirements (if applicable): Skills in numerical simulation and computational physics.

Co-funding: An monthly stipend of ~650€ will be provided in addition to the MAT-MOVE scholarship.

Project Description: When metallic nanoparticles are optically excited close to their localized surface plasmon resonance (LSPR), optical forces are induced as the result of the presence of strong local electric field induced by the surface plasmons at their surface. Here, we propose to develop a theoretical model to describe and conduct a pioneering study of these effects. Because of the multiphysics and quantum nature of this interaction, we need to develop a unique semi-classical approach that combines electrodynamics and quantum field theory. During this computational project, the student will (1) calculate the electric and magnetic fields using electrodynamics methods such as FEM, (2) use the canonical quantization of the electromagnetic fields to obtain a rigorous normalization of these fields, (3) compute the corresponding Maxwell’s Stress Tensor, and finally (4) compute the elastic energy and optical forces resulting from these fields.

Specific Requirements (if applicable): 

Project Description: The internship is devoted to photoluminescence and Raman spectroscopic studies of two-dimensional materials from the transition metal dichalcogenide family (MoS2, WS2, MoSe2...etc). These materials hold great promise for future applications in energy, catalysis and nanofiltration. They combine nanometric thickness, allowing the realisation of ultimate quantum wells, with interesting optical and electronic properties in terms of radiative excitonic emission efficiency and charge transport. The internship will allow the student to benefit from the excellent scientific environment of the LAAS-CNRS and its state-of-the-art spectrometric and structural analysis equipment (AFM, TEM). The proposed duration of the internship is at least 3 months.

Specific Requirements (if applicable): 

Project Description: 

Specific Requirements (if applicable):