Publications

2021

H2 production under gamma irradiation of a calcium aluminate cement: an experimental study on both cement pastes and its stable hydrates
- Acher Loren
- de Noirfontaine Marie-Noëlle
- Chartier David
- Gorse -Pomonti Dominique
- Courtial Mireille
- Tusseau-Nenez Sandrine
- Cavani Olivier
- Haas Jérémy
- Dannoux- Papin Adeline
- Dunstetter Frédéric
Radiation Physics and Chemistry, Elsevier, 2021, 189, pp.109689. The objective of this paper is to investigate the use of calcium aluminate cements as alternative cements within the context of nuclear waste stabilization by solidification. Using an external 60 Co source, the effect of γ-radiation on H2 gas production of one of the calcium aluminate cement-based materials (cement "Ciment Fondu") and its stable hydrates, was studied. The amount of H2 produced by these cement pastes is found to be much lower (up to five times less) than that of the Portland cement pastes containing the same amount of water, especially in the low range of water to cement ratios (W/C ≤ 0.4) where water is essentially engaged in the hydrates. The H2 production of the two major hydrates of Ciment Fondu, gibbsite AH3 and katoite hydrogarnet C3AH6, is very low compared with that of the main hydrates of other cements (Portland cement, Calcium Sulfo-Aluminate and Magnesium Phosphate cements). The type of water engaged in the hydrates, as hydroxyl groups and/or molecular water, influences significantly the H2 production. Thus, the nature of the hydrate is a key parameter to the aim of optimizing cement matrices with respect to the gas production under irradiation. XRD analysis shows that the crystal structures of gibbsite and katoite are preserved up to very high doses under electron irradiation (3 GGy). This makes calcium aluminate cements (CAC) potential good candidates for nuclear waste conditioning from the point of view of their stability under irradiation. (10.1016/j.radphyschem.2021.109689)
DOI : 10.1016/j.radphyschem.2021.109689
High-temperature quantum anomalous Hall regime in a MnBi2Te4/Bi2Te3 superlattice
- Deng Haiming
- Chen Zhiyi
- Wołoś Agnieszka
- Konczykowski Marcin
- Sobczak Kamil
- Sitnicka Joanna
- Fedorchenko Irina V
- Borysiuk Jolanta
- Heider Tristan
- Pluciński Łukasz
- Park Kyungwha
- Georgescu Alexandru B
- Cano Jennifer
- Krusin-Elbaum Lia
Nature Physics, Nature Publishing Group [2005-....], 2021, 17 (1), pp.36-42. (10.1038/s41567-020-0998-2)
DOI : 10.1038/s41567-020-0998-2
Key parameters for surface plasma wave excitation in the ultra-high intensity regime
- Marini S
- Kleij P S
- Amiranoff F
- Grech M
- Riconda C
- Raynaud Michèle
Physics of Plasmas, American Institute of Physics, 2021, 28 (7), pp.073104. Ultra-short high-power lasers can deliver extreme light intensities (!10 20 W/cm 2 and 30 f s) and drive large amplitude Surface Plasma Wave (SPW) at over-dense plasma surface. The resulting current of energetic electron has great interest for applications, potentially scaling with the laser amplitude, provided that the laser-plasma transfer to the accelerated particles mediated by SPW is still efficient at ultra-high intensity. By means of particle-in-cell simulations, we identify the best condition for SPW excitation and show a strong correlation between the optimum surface plasma wave excitation angle and the laser's angle of incidence that optimize the electron acceleration along the plasma surface. We also discuss how plasma density and plasma surface shape can be adjusted in order to push to higher laser intensity the limit of surface plasma wave excitation. Our results open the way to new experiments on forthcoming multi-petawatt laser systems. (10.1063/5.0052599)
DOI : 10.1063/5.0052599
Exciton band structure of Molybdenum Disulfide: from monolayer to bulk
- Fugallo Giorgia
- Cudazzo Pierluigi
- Gatti Matteo
- Sottile Francesco
Electronic Structure, IOPScience, 2021, 3 (1), pp.014005. Exciton band structures analysis provides a powerful tool to identify the exciton character of materials, from bulk to isolated systems, and goes beyond the mere analysis of the optical spectra. In this work, we focus on the exciton properties of Molibdenum Disulfide (MoS2) by solving the ab initio many-body Bethe-Salpeter equation, as a function of momentum, to obtain the excitation spectra of both monolayer and bulk MoS2. We analyse the spectrum and the exciton dispersion on the basis of a model excitonic Hamiltonian capable of providing an efficient description of the excitations in the bulk crystal, starting from the knowledge of the excitons of a single layer. In this way, we obtain a general characterization of both bright and darks excitons in terms of the interplay between the electronic band dispersion (i.e. interlayer hopping) and the electron-hole exchange interaction. We identify for both the 2D and the 3D limiting cases the character of the lowestenergy excitons in MoS2, we explain the effects and relative weights of both band dispersion and electron-hole exchange interaction and finally we interpret the differences observed when changing the dimensionality of the system. (10.1088/2516-1075/abdb3c)
DOI : 10.1088/2516-1075/abdb3c
Systemic consequences of disorder in magnetically self-organized topological MnBi$_2$Te$_4$/(Bi$_2$Te$_3$)$n$ superlattices
- Sitnicka Joanna
- Park Kyungwha
- Skupiński Paweł
- Grasza Krzysztof
- Reszka Anna
- Sobczak Kamil
- Borysiuk Jolanta
- Adamus Zbigniew
- Tokarczyk Mateusz
- Avdonin Andrei
- Fedorchenko Irina
- Abaloszewa Irina
- Turczyniak-Surdacka Sylwia
- Olszowska Natalia
- Kołodziej Jacek
- Kowalski Bogdan J
- Deng Haiming
- Konczykowski Marcin
- Krusin-Elbaum Lia
- Wołoś Agnieszka
2D Materials, IOP Publishing, 2021, 9 (1), pp.015026. MnBi$_2$Te$_4$/(Bi$_2$Te$_3$)$n$ materials system has recently generated strong interest as a natural platform for the realization of the quantum anomalous Hall (QAH) state. The system is magnetically much better ordered than substitutionally doped materials, however, the detrimental effects of certain disorders are becoming increasingly acknowledged. Here, from compiling structural, compositional, and magnetic metrics of disorder in ferromagnetic (FM) MnBi$_2$Te$_4$/(Bi$_2$Te$_3$)$n$ it is found that migration of Mn between MnBi$_2$Te$_4$ septuple layers (SLs) and otherwise non-magnetic Bi$_2$Te$_3$ quintuple layers (QLs) has systemic consequences—it induces FM coupling of Mn-depleted SLs with Mn-doped QLs, seen in ferromagnetic resonance as an acoustic and optical resonance mode of the two coupled spin subsystems. Even for a large SL separation ( n ≳ 4 QLs) the structure cannot be considered as a stack of uncoupled two-dimensional layers. Angle-resolved photoemission spectroscopy and density functional theory studies show that Mn disorder within an SL causes delocalization of electron wave functions and a change of the surface band structure as compared to the ideal MnBi$_2$Te$_4$/(Bi$_2$Te$_3$)$n$. These findings highlight the critical importance of inter- and intra-SL disorder towards achieving new QAH platforms as well as exploring novel axion physics in intrinsic topological magnets. (10.1088/2053-1583/ac3cc6)
DOI : 10.1088/2053-1583/ac3cc6
Hyperbolic plasmonics with anisotropic gain–loss metasurfaces
- Kuzmin Dmitry
- Bychkov Igor
- Shavrov Vladimir
- Temnov Vasily
Optics Letters, Optical Society of America - OSA Publishing, 2021, 46 (2), pp.420. In this Letter, a fundamentally new concept of realization of hyperbolic plasmonic metasurfaces by anisotropic gain–loss competition is proposed, and the possibility of highly directional propagation and amplification of surface plasmon polaritons is predicted. A simple realistic configuration of such a metasurface represents the periodic array of lossy metallic slabs embedded in the gain matrix. Our results may pave the way for numerous applications ranging from integrated and highly directional quantum light emitters to nonlinear-optical frequency converters. (10.1364/OL.413511)
DOI : 10.1364/OL.413511

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