Valley relaxation due to exciton-phonon coupling a,b) False color map of the circularly polarized PL emission from IX of S1 measured with a resolution of 10 mT in the vicinity of the two identified resonant magnetic fields. c,d) Peak position and intensity (proportional to the size of the symbol) of the polarized IX emission. The excitonic Zeeman splitting is tuned in resonance with two characteristic energies of 22.3 and 22.95 meV for which a very efficient thermalization of the excitons towards the lowest energy component is observed. The inset in panel d sketches the thermalization between the valleys mediated with help of a chiral phonon with L = +1. e) Zeeman splitting of the IX as function of the magnetic field, which shows that the energy of the chiral phonons in WSe2 and MoSe2 are crossed between 24 and 25 T.

Valley relaxation due to exciton-phonon coupling a,b) False color map of the circularly polarized PL emission from IX of S1 measured with a resolution of 10 mT in the vicinity of the two identified resonant magnetic fields. c,d) Peak position and intensity (proportional to the size of the symbol) of the polarized IX emission. The excitonic Zeeman splitting is tuned in resonance with two characteristic energies of 22.3 and 22.95 meV for which a very efficient thermalization of the excitons towards the lowest energy component is observed. The inset in panel d sketches the thermalization between the valleys mediated with help of a chiral phonon with L = +1. e) Zeeman splitting of the IX as function of the magnetic field, which shows that the energy of the chiral phonons in WSe2 and MoSe2 are crossed between 24 and 25 T.

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Optical selection rules in monolayers of transition metal dichalcogenides and of their heterostructures are determined by the conservation of the z-component of the total angular momentum - J Z = L Z +S Z - associated with the C3 rotational lattice symmetry which assumes half integer values corresponding, modulo 3, to distinct states. Here we show,...

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... giant g-factor associated with IX −1 in 60 • aligned MoSe 2 /WSe 2 heterobilayer allows one to tune the Zeeman energy up to few tens of meV with magnetic fields available in high magnetic fields infrastructures. In Fig Figure 3c and 3d for each extinction respectively, the intensity of the lower energy σ+ component grows and decreases back to its initial value for higher magnetic fields. The excitonic emission does not show any significant energy shift nor broadening during the resonance. ...
Context 2
... resonant magnetic fields correspond to an excitonic Zeeman energy of E Z = 22.30 meV and 22.95 meV, respectively. Striking is the narrow field interval where the energy relaxation occurs: its width of ∼ 150 mT corresponds to 22.3 meV 179.9 cm -1 22.95 meV 185.1 cm -1 the change in E Z of 150 µeV, as presented in Figure 3a,b. This indicates a resonance with a mode with a very well defined energy, which couples IX excitons of different polarizations (i.e. from different valleys). ...
Context 3
... giant g-factor associated with IX −1 in 60 • aligned MoSe 2 /WSe 2 heterobilayer allows one to tune the Zeeman energy up to few tens of meV with magnetic fields available in high magnetic fields infrastructures. In Fig Figure 3c and 3d for each extinction respectively, the intensity of the lower energy σ+ component grows and decreases back to its initial value for higher magnetic fields. The excitonic emission does not show any significant energy shift nor broadening during the resonance. ...
Context 4
... resonant magnetic fields correspond to an excitonic Zeeman energy of E Z = 22.30 meV and 22.95 meV, respectively. Striking is the narrow field interval where the energy relaxation occurs: its width of ∼ 150 mT corresponds to 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 A c c e p t e d M a n u s c r i p t 22.3 meV 179.9 cm -1 22.95 meV 185.1 cm -1 the change in E Z of 150 µeV, as presented in Figure 3a,b. This indicates a resonance with a mode with a very well defined energy, which couples IX excitons of different polarizations (i.e. from different valleys). ...
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... are not Raman active in monolayers and we could not detect them in our heterobilayers (see Supplementary Information Section S6). The angular momentum L z = ±1 [22,38,39] carried by this phonon can however be transferred to the electronic system, as sketched in the inset of Figure 3d [43]. A similar situation has been also observed in the case of E 2g phonons in graphene or in graphite [44][45][46]. ...

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... Chiral phonons were studied in many two dimensional (2D) lattices, e.g., honeycomb lattice [1,2], kagome lattice [3], or moiré superlattices [4]. Recently, chiral phonons were also reported in many three dimensional (3D) materials, e.g.: transition metal dichalcogenides [5][6][7][8] and their heterostructures [9][10][11], pervoskites [12][13][14][15], graphene/hexagonal boron nitride heterostructure [16], 2D magnets (CrBr 3 [17] or Fe 3 GeTe 2 [18]), cuprates [19], CoSn-like systems [20], ternary YAlSi compound [21], chiral systems (ABi-like compounds [22], α-HgS [23] or SiO 4 [24]), and magnetic topological insulators T Bi 2 Te 4 [25]. Due to their extraordinary properties (e.g., realization of the phonon Hall effect [26][27][28][29][30][31][32][33]), it has attracted a lot of theoretical and experimental attentions. ...
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