Séminaire LCPMR | Meryem Bouaziz "Phase transitions in two-dimensional layered materials"
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Le 12 fév. 2025
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11:00 - 12:00
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Séminaire
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Sorbonne Université, campus Pierre et Marie Curie
UFR de Chimie, salle 101 tour 32-42
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Carniato Stéphane
| SÉMINAIRE | Personnalité invitée |
| Titre |
PHASE TRANSITIONS IN TWO-DIMENSIONAL LAYERED MATERIALS |
| Présenté par | |
| Affectation | Centre de Nanosciences et de Nanotechnologies (C2N), CNRS, Université Paris Saclay |
| Résumé | Two-dimensional (2D) materials have been extensively studied since the successful isolation of graphene1. Typical families of graphene-like 2D materials, such as hexagonal boron nitride (hBN), phosphorene and transition metal dichalcogenides (TMDs), offer many interesting electronic properties (semiconductor, ferroelectric and topological phase)2 due to their unique structures, paving the way towards various applications. In particular, different 2D layered semiconductors can be easily combined to form a variety of vertical van der Waals (vdW) heterostructures, with atomically sharp interfaces and tunable band alignment. I will first present the structural and electronic properties of a monolayer of tellurium based 2D materials on noble metal substrates (Cu2Te and tellurene). These properties are modulated in a monolayer under the effect of temperature annealing and also show a thickness-dependent phase transition3,4. Second, I will focus on the properties of bilayer tungsten diselenide (WSe2), which exhibits strong spin-orbit coupling among TMDs materials. I will present the properties of different WSe2 bilayer stacking: 2H, 3R and 1T’. In particular, the 3R bilayer is formed by AB stacking sequences which develop spontaneous out-of-plane electrical polarisation, leading to a ferroelectric effect5,6. References: 1. Geim, A. K. & Grigorieva, I. V. Van der Waals Heterostructures. Nature 499, 419–425 (2013). 2. Wang, X. et al. Interfacial ferroelectricity in rhombohedral-stacked bilayer transition metal dichalcogenides. Nat. Nanotechnol. 17, 367–371 (2022). 3. Bouaziz, M. et al. Phase transition from Au–Te surface alloy towards tellurene-like monolayer. 2D Mater. 8, 015029 (2021). 4. Tong, Y. et al. Evidence of new 2D material: Cu2 Te. 2D Mater. 7, 035010 (2020). 5. Mahmoudi, A. et al. Electronic properties of rhombohedrally stacked bilayer WSe2 obtained by chemical vapor deposition. Phys. Rev. B 108, 045417 (2023). 6. Mahmoudi, A. et al. Quasi van der Waals Epitaxy of Rhombohedral-Stacked Bilayer WSe2 on GaP(111) Heterostructure. ACS Nano 17, 21307–21316 (2023). |
| Contact LCPMR | Stéphane Carniato |