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Physique de l'exciton, du photon et du spin
(54) Production(s) de l'année 2019
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Non-Markovian transient Casimir-Polder force and population dynamics on excited- and ground-state atoms: Weak- and strong-coupling regimes in generally nonreciprocal environments 
Auteur(s): Hanson George W., Hassani Gangaraj S. Ali, Silveirinha Mario, Antezza M., Monticone Francesco
(Article) Publié:
-Physical Review A Atomic, Molecular, And Optical Physics [1990-2015], vol. 99 p.042508 (2019)
Texte intégral en Openaccess : 
Ref HAL: hal-02103569_v1
DOI: 10.1103/PhysRevA.99.042508
WoS: 000465146800004
Exporter : BibTex | endNote
Résumé: The transient Casimir-Polder force on a two-level atom introduced into a three-dimensional, inhomogeneous, generally nonreciprocal environment is evaluated using non-Markovian Weisskopf-Wigner theory in the strong- and weak-coupling regimes. Ground-state and excited atoms are shown to decouple into two separate initial-value problems, and both the short-time and long-time atomic population and force are evaluated. The results are compared with various Markov approximations of the Weisskopf-Wigner theory and with previous Markov results from the Heisenberg picture.
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Current-Induced Nucleation and Dynamics of Skyrmions in a Co-based Hensler Alloy
Auteur(s): Akhtar W., Hrabec A., Chouaieb S., Haykal A., Gross I., Belmeguenai M., Gabor M. S., Shields B., Maletinsky P., Thiaville A., Rohart S., Jacques V.
(Article) Publié:
Physical Review Applied, vol. 11 p.034066 (2019)
Texte intégral en Openaccess :
Ref HAL: hal-02100883_v1
DOI: 10.1103/PhysRevApplied.11.034066
WoS: WOS:000462958100004
Exporter : BibTex | endNote
7 Citations
Résumé: We demonstrate room-temperature stabilization of dipolar magnetic skyrmions with diameters in the range of 100 nm in a single ultrathin layer of the Heusler alloy Co2FeAl (CFA) under moderate magnetic fields. Current-induced skyrmion dynamics in microwires is studied with a scanning nitrogen-vacancy magnetometer operating in the photoluminescence quenching mode. We first demonstrate skyrmion nucleation by spin-orbit torque and show that its efficiency can be significantly improved using tilted magnetic fields, an effect that is not specific to Heusler alloys and could be advantageous for future skyrmion-based devices. We then show that current-induced skyrmion motion remains limited by strong pinning effects, even though CFA is a magnetic material with a low magnetic damping parameter.
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Influence of isotopic substitution on the anharmonicity of the interlayer shear mode of h-BN
Auteur(s): Cusco Ramon, Edgar James H., Liu Song, Cassabois G., Gil B., Artus Luis
(Article) Publié:
Physical Review B, vol. 99 p.085428 (2019)
Texte intégral en Openaccess : 
Ref HAL: hal-02086080_v1
DOI: 10.1103/PhysRevB.99.085428
WoS: WOS:000459225100013
Exporter : BibTex | endNote
5 Citations
Résumé: We present a detailed analysis of the temperature dependence of the interlayer shear mode that reveals a variation of the four-phonon scattering coupling with isotopic mass. Phonon anharmonic decay and isotopic disorder effects are very weak for the low-energy interlayer shear mode, and the overall temperature dependence is mainly governed by the thermal lattice expansion. This allows us to observe systematic differences in the temperature dependence of the low-energy mode with the isotopic mass that are related to the four-phonon scattering contribution in quartic anharmonicity. The change in the quartic anharmonicity coefficient between the isotopically pure samples is larger than would be purely expected from the mass variation.
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Optimizing the shape of InAs/InP quantum dot-nanowires grown by MBE on silicon for efficient light sources emitting in the telecom band
Auteur(s): Jaffal Ali, Regreny Philippe, Redjem W., Nguyen Hai Son, Cueff Sébastien, Letartre Xavier, Patriarche Gilles, Rousseau E., Cassabois G., Gendry Michel, Chauvin Nicolas
Conference: 20th European Workshop on Molecular Beam Epitaxy (Lenggries, DE, 2019-02-17)
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Structural and Optical Properties of Zn1-xMgxO Prepared by Calcination of ZnO + Mg(OH)2 after Hydro Micro Mechanical Activation
Auteur(s): Vuong Thi Quynh Phuong, Lair Valentin, Lacoste Francois, Halloumi Samy, Coindeau Stéphane, Thiel Julien, Shubina T., Pauthe Monique, Gil B.
(Article) Publié:
Annalen Der Physik, vol. p.1800379 (2019)
Ref HAL: hal-01992435_v1
DOI: 10.1002/andp.201800379
WoS: 000471714300010
Exporter : BibTex | endNote
Résumé: Zn1-xMgxO microcrystals are produced in the 0.15 & x & 1 composition range by calcination of ZnO + Mg(OH)2 after hydro micro mechanical activation according to the patent WO2018065735A1. The structural properties of the samples have revealed the cohabitation of wurtzite and rock-salt phases for x values ranging from 0.15 up to 0.6 with a clear increase of the proportion of cubic phase with x. A single cubic phase is observed in the range 0.66
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