Radio continuum, microwave and gamma-ray images of the Milky Way reveal a conspicuous, loop-like structure that fills almost half of the northern Galactic hemisphere, called Loop I. The interior of Loop I is shining in soft X-rays, and its eastern base is a bright, elongated structure dubbed the North Polar Spur (NPS). After 40 years of debates, two contradictory views of Loop I/NPS are still defended: on the one hand, the NPS is a volume of expanding hot gas that envelops and extends the northern Fermi Bubble (FB) known to be blown by the Galactic center, and Loop I marks the shock front; on the other hand, the NPS is a nearby cavity of hot gas blown by supernovae, Loop I is its shock front and they are coincidentally located in the direction of the FB. To an observer at the Sun, both structures can produce the same perspective view, although the former has a size comparable to the Milky Way itself, and the latter a diameter of a few hundreds parsecs. The energy involved varies by 3-4~orders of magnitude, and the solution has various important consequences. I discuss recent results which have a connection with Loop I/NPS, overlooked or used as arguments in the two opposite ways. They involve very different spacecraft, from a 12 Kg Cubesat (HaloSat) to major space-borne observatories (HST, Gaia, and Spektr-RG). I make use of 3D~maps of dust and a massive star catalog. Considering all constraints, it is clear that there is no entirely local or entirely distant scenario that is free from contradictions with some of the data analyses or from improbable coincidences. I discuss a speculative scenario, partially inspired by recent BF and Milky Way gas models, combining near and far aspects and seeming to be able to meet the various constraints. However, new data and models are needed to bring the controversy to a close and we can still expect new episodes of this long story.
{"title":"North Polar Spur/Loop I: gigantic outskirt of the Northern Fermi bubble or nearby hot gas cavity blown by supernovae?","authors":"R. Lallement","doi":"10.5802/crphys.97","DOIUrl":"https://doi.org/10.5802/crphys.97","url":null,"abstract":"Radio continuum, microwave and gamma-ray images of the Milky Way reveal a conspicuous, loop-like structure that fills almost half of the northern Galactic hemisphere, called Loop I. The interior of Loop I is shining in soft X-rays, and its eastern base is a bright, elongated structure dubbed the North Polar Spur (NPS). After 40 years of debates, two contradictory views of Loop I/NPS are still defended: on the one hand, the NPS is a volume of expanding hot gas that envelops and extends the northern Fermi Bubble (FB) known to be blown by the Galactic center, and Loop I marks the shock front; on the other hand, the NPS is a nearby cavity of hot gas blown by supernovae, Loop I is its shock front and they are coincidentally located in the direction of the FB. To an observer at the Sun, both structures can produce the same perspective view, although the former has a size comparable to the Milky Way itself, and the latter a diameter of a few hundreds parsecs. The energy involved varies by 3-4~orders of magnitude, and the solution has various important consequences. I discuss recent results which have a connection with Loop I/NPS, overlooked or used as arguments in the two opposite ways. They involve very different spacecraft, from a 12 Kg Cubesat (HaloSat) to major space-borne observatories (HST, Gaia, and Spektr-RG). I make use of 3D~maps of dust and a massive star catalog. Considering all constraints, it is clear that there is no entirely local or entirely distant scenario that is free from contradictions with some of the data analyses or from improbable coincidences. I discuss a speculative scenario, partially inspired by recent BF and Milky Way gas models, combining near and far aspects and seeming to be able to meet the various constraints. However, new data and models are needed to bring the controversy to a close and we can still expect new episodes of this long story.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48146804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Foreword: Plasticity and Solid State Physics","authors":"S. Forest, D. Rodney","doi":"10.5802/crphys.92","DOIUrl":"https://doi.org/10.5802/crphys.92","url":null,"abstract":"","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":"13 8","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41268130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Graphene is known to have small intrinsic spin-orbit Interaction (SOI). In this review, we demonstrate that SOIs in graphene can be strongly enhanced by proximity effect when graphene is deposited on the top of transition metal dichalcogenides. We discuss the symmetry of the induced SOIs and differences between TMD underlayers in the capacity of inducing strong SOIs in graphene. The strong SOIs contribute to bring novel phenomena to graphene, exemplified by robust supercurrents sustained even under tesla-range magnetic fields.
{"title":"Novel transport phenomena in graphene induced by strong spin-orbit interaction","authors":"T. Wakamura, S. Gu'eron, H. Bouchiat","doi":"10.5802/crphys.93","DOIUrl":"https://doi.org/10.5802/crphys.93","url":null,"abstract":"Graphene is known to have small intrinsic spin-orbit Interaction (SOI). In this review, we demonstrate that SOIs in graphene can be strongly enhanced by proximity effect when graphene is deposited on the top of transition metal dichalcogenides. We discuss the symmetry of the induced SOIs and differences between TMD underlayers in the capacity of inducing strong SOIs in graphene. The strong SOIs contribute to bring novel phenomena to graphene, exemplified by robust supercurrents sustained even under tesla-range magnetic fields.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43184456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Cucchi, S. Lisi, F. Margot, H. Henck, A. Tamai, F. Baumberger
Angle-resolved photoemission is a direct probe of the momentum-resolved electronic structure and proved influential in the study of bulk crystals with novel electronic properties. Thanks to recent technical advances, this technique can now be applied for the first time for the study of van der Waals heterostructures built by stacking two-dimensional crystals. In this article we will present the current state of the art in angleresolved photoemission measurements on two-dimensional materials and review this still young field. We will focus in particular on devices similar to those used in transport and optics experiments, including the latest developments on magic-angle twisted bilayer graphene and on the in-operando characterization of gate tunable devices.
{"title":"Electronic structure of 2D van der Waals crystals and heterostructures investigated by spatially- and angle-resolved photoemission","authors":"I. Cucchi, S. Lisi, F. Margot, H. Henck, A. Tamai, F. Baumberger","doi":"10.5802/crphys.91","DOIUrl":"https://doi.org/10.5802/crphys.91","url":null,"abstract":"Angle-resolved photoemission is a direct probe of the momentum-resolved electronic structure and proved influential in the study of bulk crystals with novel electronic properties. Thanks to recent technical advances, this technique can now be applied for the first time for the study of van der Waals heterostructures built by stacking two-dimensional crystals. In this article we will present the current state of the art in angleresolved photoemission measurements on two-dimensional materials and review this still young field. We will focus in particular on devices similar to those used in transport and optics experiments, including the latest developments on magic-angle twisted bilayer graphene and on the in-operando characterization of gate tunable devices.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43306747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Youcef Baamara, A. Sinatra, Manuel Gessner Lkb, Icfo
In an ensemble of two-level atoms that can be described in terms of a collective spin, entangled states can be used to enhance the sensitivity of interferometric precision measurements. While non-Gaussian spin states can produce larger quantum enhancements than spin-squeezed Gaussian states, their use requires the measurement of observables that are nonlinear functions of the three components of the collective spin. In this paper we develop strategies that achieve the optimal quantum enhancements using non-Gaussian states produced by a nonlinear one-axis-twisting Hamiltonian, and show that measurement-after-interaction techniques, known to amplify the output signals in quantum parameter estimation protocols, are effective in measuring nonlinear spin observables. Including the presence of the relevant decoherence processes from atomic experiments, we determine analytically the quantum enhancement of non-Gaussian over-squeezed states as a function of the noise parameters for arbitrary atom numbers.
{"title":"Squeezing of nonlinear spin observables by one axis twisting in the presence of decoherence: An analytical study","authors":"Youcef Baamara, A. Sinatra, Manuel Gessner Lkb, Icfo","doi":"10.5802/crphys.103","DOIUrl":"https://doi.org/10.5802/crphys.103","url":null,"abstract":"In an ensemble of two-level atoms that can be described in terms of a collective spin, entangled states can be used to enhance the sensitivity of interferometric precision measurements. While non-Gaussian spin states can produce larger quantum enhancements than spin-squeezed Gaussian states, their use requires the measurement of observables that are nonlinear functions of the three components of the collective spin. In this paper we develop strategies that achieve the optimal quantum enhancements using non-Gaussian states produced by a nonlinear one-axis-twisting Hamiltonian, and show that measurement-after-interaction techniques, known to amplify the output signals in quantum parameter estimation protocols, are effective in measuring nonlinear spin observables. Including the presence of the relevant decoherence processes from atomic experiments, we determine analytically the quantum enhancement of non-Gaussian over-squeezed states as a function of the noise parameters for arbitrary atom numbers.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42947431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Jarnac, V. Jacques, L. Cario, E. Janod, S. Johnson, S. Ravy, C. Laulhé
Recent experiments have shown that the high-temperature incommensurate (I) charge density wave (CDW) phase of 1T-TaS2 can be photoinduced from the lower-temperature, nearly commensurate CDW state. In a first step, several independent regions exhibiting I-CDW phase modulations nucleate and grow. After coalescence, these regions form a multidomain I-CDW phase that undergoes coarsening dynamics, i.e. a progressive increase of the domain size or I-CDW correlation length. Using time-resolved X-ray diffraction, we show that the wave vector of the photoinduced I-CDW phase is shorter than in the I-CDW phase at equilibrium, and progressively increases towards its equilibrium value as the correlation length increases. We interpret this behaviour as a consequence of a self-doping of the photoinduced I-CDW, following the presence of trapped electrons in the vicinity of CDW dislocation sites. Putting together results of the present and past experiments, we develop a scenario in which the I-CDW dislocations are created during the coalescence of the I-CDW phase regions. Résumé. Plusieurs expériences récentes ont montré que les impulsions laser dans les domaines optique ou proche infrarouge permettent de déclencher des transitions entre états à onde de densité de charge (ODC) dans 1T-TaS2. Nous nous intéressons ici à la transition entre l’état à ODC presque commensurable (NC) ∗Corresponding author. ISSN (electronic) : 1878-1535 https://comptes-rendus.academie-sciences.fr/physique/ 2 Amélie Jarnac et al. et l’état à ODC incommensurable (I), habituellement observé au-dessus de 350 K. Lors de cette transition, plusieurs régions présentant les modulations de l’état I se forment et se développent. Lorsque la coalescence a lieu, ces régions se muent en domaines de la phase I photoinduite de 1T-TaS2, caractérisés chacun par un phasage particulier de l’ODC I. La phase I ainsi fragmentée en domaines subit alors une dynamique de mûrissement, c’est-à-dire une augmentation progressive de la taille de domaine ou encore de la longueur de corrélation de l’ODC I. En utilisant la diffraction des rayons X résolue en temps, nous montrons que le vecteur d’onde de l’ODC I photoinduite est plus court que dans l’ODC I observée à l’équilibre thermodynamique. Celui-ci s’allonge progressivement vers sa valeur d’équilibre, en même temps que la longueur de corrélation de l’ODC I augmente. Nous attribuons ce comportement à un autodopage de l’ODC I photoinduite, dû à la présence d’électrons piégés au voisinage de dislocations de l’ODC I. En réalisant une synthèse des résultats des différentes expériences menées jusqu’à présent, nous développons un scénario dans lequel les dislocations de l’ODC I sont créées au moment de la coalescence.
{"title":"Photoinduced charge density wave phase in 1T-TaS 2 : growth and coarsening mechanisms","authors":"A. Jarnac, V. Jacques, L. Cario, E. Janod, S. Johnson, S. Ravy, C. Laulhé","doi":"10.5802/crphys.89","DOIUrl":"https://doi.org/10.5802/crphys.89","url":null,"abstract":"Recent experiments have shown that the high-temperature incommensurate (I) charge density wave (CDW) phase of 1T-TaS2 can be photoinduced from the lower-temperature, nearly commensurate CDW state. In a first step, several independent regions exhibiting I-CDW phase modulations nucleate and grow. After coalescence, these regions form a multidomain I-CDW phase that undergoes coarsening dynamics, i.e. a progressive increase of the domain size or I-CDW correlation length. Using time-resolved X-ray diffraction, we show that the wave vector of the photoinduced I-CDW phase is shorter than in the I-CDW phase at equilibrium, and progressively increases towards its equilibrium value as the correlation length increases. We interpret this behaviour as a consequence of a self-doping of the photoinduced I-CDW, following the presence of trapped electrons in the vicinity of CDW dislocation sites. Putting together results of the present and past experiments, we develop a scenario in which the I-CDW dislocations are created during the coalescence of the I-CDW phase regions. Résumé. Plusieurs expériences récentes ont montré que les impulsions laser dans les domaines optique ou proche infrarouge permettent de déclencher des transitions entre états à onde de densité de charge (ODC) dans 1T-TaS2. Nous nous intéressons ici à la transition entre l’état à ODC presque commensurable (NC) ∗Corresponding author. ISSN (electronic) : 1878-1535 https://comptes-rendus.academie-sciences.fr/physique/ 2 Amélie Jarnac et al. et l’état à ODC incommensurable (I), habituellement observé au-dessus de 350 K. Lors de cette transition, plusieurs régions présentant les modulations de l’état I se forment et se développent. Lorsque la coalescence a lieu, ces régions se muent en domaines de la phase I photoinduite de 1T-TaS2, caractérisés chacun par un phasage particulier de l’ODC I. La phase I ainsi fragmentée en domaines subit alors une dynamique de mûrissement, c’est-à-dire une augmentation progressive de la taille de domaine ou encore de la longueur de corrélation de l’ODC I. En utilisant la diffraction des rayons X résolue en temps, nous montrons que le vecteur d’onde de l’ODC I photoinduite est plus court que dans l’ODC I observée à l’équilibre thermodynamique. Celui-ci s’allonge progressivement vers sa valeur d’équilibre, en même temps que la longueur de corrélation de l’ODC I augmente. Nous attribuons ce comportement à un autodopage de l’ODC I photoinduite, dû à la présence d’électrons piégés au voisinage de dislocations de l’ODC I. En réalisant une synthèse des résultats des différentes expériences menées jusqu’à présent, nous développons un scénario dans lequel les dislocations de l’ODC I sont créées au moment de la coalescence.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48150471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
. The superconductivity confined in a two-dimensional interface exhibits many exotic phenomena that have certain counterparts in layered cuprates and iron-based superconductors, and thus provides rare opportunities to reveal the mystery of high temperature superconductivity therein. By constructing and tailoring hybrid heterostructures such as FeSe/SrTiO 3 (FeSe/STO), interface-enhanced superconductivity arouses, and the substrate has been demonstrated to provide the phonons and enhance the strong electron– phonon coupling (EPC) withinmonolayer FeSe. More research and reporting systems uncover that the band-bending induced charge transfer at the interface could become a unified microscopic picture to design the andunconventionalsuperconductors,thecommoncharacteristicssuchasbandbendingandrigidbandshift are perceived in the FeSe/STO, LAO/STO and cuprate superconductors. This review may provide important information to inspect the mechanism of high- T c superconductivity from a di ff erent view. a unified microscopic picture on how the interface superconductivity is prompted remains puzzling. For this purpose, we not only review the experimental research including spectroscopic study of 1UC FeSe/STO, CuO 2 /Bi2212, but also reexamine the previous results of LAO/STO [31] and even cuprate superconductors, and aim to capture the common characteristics among them. The ef-fects of charge transfer and band alignment are discussed first in the four systems. Then the rigid band shift and EPC are examined in the 1UC FeSe/STO, cuprates and LAO/STO systems. The polar nature’s influence on LAO/STO and cuprate on the tilted band structure is highlighted. All dis-cussions include the similar token in cuprates and may provide more insights into understanding
{"title":"Interface enhanced superconductivity in FeSe/SrTiO 3 and the hidden nature","authors":"Sha Han, C. Song, Xu-Cun Ma, Q. Xue","doi":"10.5802/crphys.87","DOIUrl":"https://doi.org/10.5802/crphys.87","url":null,"abstract":". The superconductivity confined in a two-dimensional interface exhibits many exotic phenomena that have certain counterparts in layered cuprates and iron-based superconductors, and thus provides rare opportunities to reveal the mystery of high temperature superconductivity therein. By constructing and tailoring hybrid heterostructures such as FeSe/SrTiO 3 (FeSe/STO), interface-enhanced superconductivity arouses, and the substrate has been demonstrated to provide the phonons and enhance the strong electron– phonon coupling (EPC) withinmonolayer FeSe. More research and reporting systems uncover that the band-bending induced charge transfer at the interface could become a unified microscopic picture to design the andunconventionalsuperconductors,thecommoncharacteristicssuchasbandbendingandrigidbandshift are perceived in the FeSe/STO, LAO/STO and cuprate superconductors. This review may provide important information to inspect the mechanism of high- T c superconductivity from a di ff erent view. a unified microscopic picture on how the interface superconductivity is prompted remains puzzling. For this purpose, we not only review the experimental research including spectroscopic study of 1UC FeSe/STO, CuO 2 /Bi2212, but also reexamine the previous results of LAO/STO [31] and even cuprate superconductors, and aim to capture the common characteristics among them. The ef-fects of charge transfer and band alignment are discussed first in the four systems. Then the rigid band shift and EPC are examined in the 1UC FeSe/STO, cuprates and LAO/STO systems. The polar nature’s influence on LAO/STO and cuprate on the tilted band structure is highlighted. All dis-cussions include the similar token in cuprates and may provide more insights into understanding","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47332006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Levantino, Q. Kong, M. Cammarata, D. Khakhulin, F. Schotte, P. Anfinrud, V. Kabanova, H. Ihee, A. Plech, S. Bratos, M. Wulff
This review focuses on how short X-ray pulses from synchrotrons and XFELs can be used to track light-induced structural changes in molecular complexes and proteins via the pump–probe method. The upgrade of the European Synchrotron Radiation Facility to a diffraction-limited storage ring, based on the seven-bend achromat lattice, and how it might boost future pump–probe experiments are described. We discuss some of the first X-ray experiments to achieve 100 ps time resolution, including the dissociation and in-cage recombination of diatomic molecules, as probed by wide-angle X-ray scattering, and the 3D filming of ligand transport in myoglobin, as probed by Laue diffraction. Finally, the use of femtosecond XFEL pulses to investigate primary chemical reactions, bond breakage and bond formation, isomerisation and electron transfer are discussed.
{"title":"Structural dynamics probed by X-ray pulses from synchrotrons and XFELs","authors":"M. Levantino, Q. Kong, M. Cammarata, D. Khakhulin, F. Schotte, P. Anfinrud, V. Kabanova, H. Ihee, A. Plech, S. Bratos, M. Wulff","doi":"10.5802/crphys.85","DOIUrl":"https://doi.org/10.5802/crphys.85","url":null,"abstract":"This review focuses on how short X-ray pulses from synchrotrons and XFELs can be used to track light-induced structural changes in molecular complexes and proteins via the pump–probe method. The upgrade of the European Synchrotron Radiation Facility to a diffraction-limited storage ring, based on the seven-bend achromat lattice, and how it might boost future pump–probe experiments are described. We discuss some of the first X-ray experiments to achieve 100 ps time resolution, including the dissociation and in-cage recombination of diatomic molecules, as probed by wide-angle X-ray scattering, and the 3D filming of ligand transport in myoglobin, as probed by Laue diffraction. Finally, the use of femtosecond XFEL pulses to investigate primary chemical reactions, bond breakage and bond formation, isomerisation and electron transfer are discussed.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48604090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Dutreix, H. González-Herrero, I. Brihuega, M. Katsnelson, C. Chapelier, V. Renard
The Berry phase of wave functions is a key quantity to understand various low-energy properties of matter, among which electric polarisation, orbital magnetism, as well as topological and ultra-relativistic phenomena. Standard approaches to probe the Berry phase in solids rely on the electron dynamics in response to electromagnetic forces. In graphene, probing the Berry phase π of the massless relativistic electrons requires an external magnetic field. Here, we show that the Berry phase also affects the static response of the electrons to a single atomic scatterer, through wavefront dislocations in the surrounding standing-wave interference. This provides a new experimental method to measure the graphene Berry phase in the absence of any magnetic field and demonstrates that local disorder can be exploited as probe of topological quantum matter in scanning tunnelling microscopy experiments. Résumé. Les interférences de quasiparticules observées par microscopie à effet tunnel sont particulièrement utiles pour étudier les propriétés électroniques de matériaux en surfaces. Ces interférences possèdent des informations sur la surface de Fermi du système et leur résolution en énergie permet, dans certains cas, de reconstruire la relation dispersion. Nous montrons ici que les images d’interférences de quasiparticules peuvent aussi contenir une information sur la phase de Berry qui caractérise la structure de bande du matériau. La phase de Berry est une phase géométrique que les fonctions d’onde electroniques acquièrent lors d’une évolution cyclique dans un espace de paramètres. Elle est quantifiée lorsque la trajectoire de ∗Corresponding authors. ISSN (electronic) : 1878-1535 https://comptes-rendus.academie-sciences.fr/physique/ 2 Clément Dutreix et al. l’évolution ensèrre une singularité des fonctions d’onde. Il s’agit alors d’une propriété topologique de la structure de bande. La phase de Berry dans les solides est traditionnellement mesurée en appliquant des champs électromagnétiques pour forcer les particules à former de trajectoires fermées. L’utilisation de la figure d’interférence de quasiparticules permet de s’extraire de ce paradigme car la phase de Berry peut affecter la réponse statique des électrons au désordre en l’absence de champ électromagnétique.
波函数的Berry相是理解物质各种低能性质的关键量，其中包括电极化、轨道磁性、拓扑和超相对论现象。探测固体中贝里相的标准方法依赖于响应电磁力的电子动力学。在石墨烯中，探测无质量相对论电子的贝里相π需要外部磁场。在这里，我们表明，通过周围驻波干涉中的波前位错，贝里相位也会影响电子对单个原子散射体的静态响应。这为在没有任何磁场的情况下测量石墨烯莓相提供了一种新的实验方法，并证明了局部无序可以在扫描隧道显微镜实验中用作拓扑量子物质的探针。的简历。准粒子间的交换，观察，显微镜下的交换，效应隧道，特定的交换，表面上的交换，固有的交换，电子的交换。在某些情况下，在Fermi du system系统表面上的信息和在某些情况下，在某些情况下，重新建立了离散关系。“不确定的数据”是指“交叉的数据”和“准粒子的数据”;“不确定的数据”是指“交叉的数据”和“交叉的数据”。“贝瑞阶段”是指“通过电子交换功能获得的电子交换功能和电子交换空间获得的电子交换功能和电子交换功能和电子交换功能”的阶段。通讯作者。[2] classment Dutreix et al. l ' - - - - - - - - - - - - - - - - - -]我的意思是，我的意思是，我的意思是，我的意思是，我的意思是，我的意思是。在过去的几个月里，有一段时间是由传统因素决定的。利用“准粒子间的电子交换”这一概念，就可以利用“特殊的电子交换模式”这一概念来确定“特定的电子交换模式”，从而确定“特定的电子交换模式”，即“特定的电子交换模式”。
{"title":"Measuring graphene’s Berry phase at B=0 T","authors":"C. Dutreix, H. González-Herrero, I. Brihuega, M. Katsnelson, C. Chapelier, V. Renard","doi":"10.5802/crphys.79","DOIUrl":"https://doi.org/10.5802/crphys.79","url":null,"abstract":"The Berry phase of wave functions is a key quantity to understand various low-energy properties of matter, among which electric polarisation, orbital magnetism, as well as topological and ultra-relativistic phenomena. Standard approaches to probe the Berry phase in solids rely on the electron dynamics in response to electromagnetic forces. In graphene, probing the Berry phase π of the massless relativistic electrons requires an external magnetic field. Here, we show that the Berry phase also affects the static response of the electrons to a single atomic scatterer, through wavefront dislocations in the surrounding standing-wave interference. This provides a new experimental method to measure the graphene Berry phase in the absence of any magnetic field and demonstrates that local disorder can be exploited as probe of topological quantum matter in scanning tunnelling microscopy experiments. Résumé. Les interférences de quasiparticules observées par microscopie à effet tunnel sont particulièrement utiles pour étudier les propriétés électroniques de matériaux en surfaces. Ces interférences possèdent des informations sur la surface de Fermi du système et leur résolution en énergie permet, dans certains cas, de reconstruire la relation dispersion. Nous montrons ici que les images d’interférences de quasiparticules peuvent aussi contenir une information sur la phase de Berry qui caractérise la structure de bande du matériau. La phase de Berry est une phase géométrique que les fonctions d’onde electroniques acquièrent lors d’une évolution cyclique dans un espace de paramètres. Elle est quantifiée lorsque la trajectoire de ∗Corresponding authors. ISSN (electronic) : 1878-1535 https://comptes-rendus.academie-sciences.fr/physique/ 2 Clément Dutreix et al. l’évolution ensèrre une singularité des fonctions d’onde. Il s’agit alors d’une propriété topologique de la structure de bande. La phase de Berry dans les solides est traditionnellement mesurée en appliquant des champs électromagnétiques pour forcer les particules à former de trajectoires fermées. L’utilisation de la figure d’interférence de quasiparticules permet de s’extraire de ce paradigme car la phase de Berry peut affecter la réponse statique des électrons au désordre en l’absence de champ électromagnétique.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47390059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using a phase field model, we have investigated the role of plasticity on the morphological evolution of a precipitate during its diffusion-controlled dissolution, when submitted to shear loading. It is shown that the plastic strain pattern in the matrix strongly influences the local dissolution rate and consequently the final shape of the precipitate. Finally, it is demonstrated that for sufficiently fast and intense shear loadings, plasticity can induce splitting of the precipitate: this process could explain why small precipitates are observed in shear bands in Ti alloys forged parts.
{"title":"Splitting of dissolving precipitates during plastic shear: A phase field study","authors":"K. Ammar, B. Appolaire, S. Forest","doi":"10.5802/crphys.82","DOIUrl":"https://doi.org/10.5802/crphys.82","url":null,"abstract":"Using a phase field model, we have investigated the role of plasticity on the morphological evolution of a precipitate during its diffusion-controlled dissolution, when submitted to shear loading. It is shown that the plastic strain pattern in the matrix strongly influences the local dissolution rate and consequently the final shape of the precipitate. Finally, it is demonstrated that for sufficiently fast and intense shear loadings, plasticity can induce splitting of the precipitate: this process could explain why small precipitates are observed in shear bands in Ti alloys forged parts.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41728615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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