CEQUINOR   05415
CENTRO DE QUIMICA INORGANICA "DR. PEDRO J. AYMONINO"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Far Infrared near normal specular reflectivty of Nix(SiO2)1-x (x=1.0,0.84,0.75,0.61,0.54,0.28) granular films
Autor/es:
NESTOR E. MASSA; JULIANO C. DERNARDIN; LEANDRO M. SOCOLOVSKY; MARCELO KNOBEL; XIXIANG ZHANG
Lugar:
Valparaiso, Chile
Reunión:
Congreso; Solidos 09; 2009
Institución organizadora:
Comite ad-hoc
Resumen:
Paper # ____ Far Infrared Near Normal Specular Reflectivity of Nix(SiO2)1-x, (x= 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) Films Néstor E. Massa1, Juliano C. Denardin2, Leandro M. Socolovsky3, Marcelo Knobel4, and X. X. Zhang5. and X. X. Zhang5. (x= 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) Films Néstor E. Massa1, Juliano C. Denardin2, Leandro M. Socolovsky3, Marcelo Knobel4, and X. X. Zhang5. and X. X. Zhang5. x(SiO2)1-x, (x= 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) Films Néstor E. Massa1, Juliano C. Denardin2, Leandro M. Socolovsky3, Marcelo Knobel4, and X. X. Zhang5. and X. X. Zhang5. Far Infrared Near Normal Specular Reflectivity of Nix(SiO2)1-x, (x= 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) Films Néstor E. Massa1, Juliano C. Denardin2, Leandro M. Socolovsky3, Marcelo Knobel4, and X. X. Zhang5. and X. X. Zhang5. (x= 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) Films Néstor E. Massa1, Juliano C. Denardin2, Leandro M. Socolovsky3, Marcelo Knobel4, and X. X. Zhang5. and X. X. Zhang5. x(SiO2)1-x, (x= 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) Films Néstor E. Massa1, Juliano C. Denardin2, Leandro M. Socolovsky3, Marcelo Knobel4, and X. X. Zhang5. and X. X. Zhang5. Far Infrared Near Normal Specular Reflectivity of Nix(SiO2)1-x, (x= 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) Films Néstor E. Massa1, Juliano C. Denardin2, Leandro M. Socolovsky3, Marcelo Knobel4, and X. X. Zhang5. and X. X. Zhang5. (x= 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) Films Néstor E. Massa1, Juliano C. Denardin2, Leandro M. Socolovsky3, Marcelo Knobel4, and X. X. Zhang5. and X. X. Zhang5. (x= 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) Films Néstor E. Massa1, Juliano C. Denardin2, Leandro M. Socolovsky3, Marcelo Knobel4, and X. X. Zhang5. and X. X. Zhang5. and X. X. Zhang5. 1Laboratorio Nacional de Investigación y Servicios en Espectroscopía Optica-CEQUINOR, Universidad Nacional de La Plata.,1900 La Plata, Argentina, Universidad Nacional de La Plata.,1900 La Plata, Argentina, Laboratorio Nacional de Investigación y Servicios en Espectroscopía Optica-CEQUINOR, Universidad Nacional de La Plata.,1900 La Plata, Argentina, 2Departamento de Física, Universidad de Santiago de Chile, Av. Ecuador 3493, Santiago, Chile, 3Instituto de Tecnologías y Ciencias de la Ingeniería, Universidad de Buenos Aires, Av. Paseo Colón 850, Buenos Aires, Argentina, Av. Paseo Colón 850, Buenos Aires, Argentina, Instituto de Tecnologías y Ciencias de la Ingeniería, Universidad de Buenos Aires, Av. Paseo Colón 850, Buenos Aires, Argentina, 4Instituto de Física, UNICAMP,13083-870, Campinas-SP, Brazil, Instituto de Física, UNICAMP,13083-870, Campinas-SP, Brazil, 5Research and Development, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia. Thuwal, Saudi Arabia. Research and Development, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia. Av. Ecuador 3493, Santiago, Chile, 3Instituto de Tecnologías y Ciencias de la Ingeniería, Universidad de Buenos Aires, Av. Paseo Colón 850, Buenos Aires, Argentina, Av. Paseo Colón 850, Buenos Aires, Argentina, Instituto de Tecnologías y Ciencias de la Ingeniería, Universidad de Buenos Aires, Av. Paseo Colón 850, Buenos Aires, Argentina, 4Instituto de Física, UNICAMP,13083-870, Campinas-SP, Brazil, Instituto de Física, UNICAMP,13083-870, Campinas-SP, Brazil, 5Research and Development, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia. Thuwal, Saudi Arabia. Research and Development, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia. Departamento de Física, Universidad de Santiago de Chile, Av. Ecuador 3493, Santiago, Chile, 3Instituto de Tecnologías y Ciencias de la Ingeniería, Universidad de Buenos Aires, Av. Paseo Colón 850, Buenos Aires, Argentina, Av. Paseo Colón 850, Buenos Aires, Argentina, Instituto de Tecnologías y Ciencias de la Ingeniería, Universidad de Buenos Aires, Av. Paseo Colón 850, Buenos Aires, Argentina, 4Instituto de Física, UNICAMP,13083-870, Campinas-SP, Brazil, Instituto de Física, UNICAMP,13083-870, Campinas-SP, Brazil, 5Research and Development, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia. Thuwal, Saudi Arabia. Research and Development, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia. email address corresponding author: neemmassa@gmail.com We report on ~550 nm thick superpara-magnetic films of Nix(SiO2)1-x (x= 1.0, ~0.84, ~0.75, ~0.61, ~0.54, ~0.2), made of Ni nanograins cosputtered with SiO2, studied by temperature dependent far infrared reflectivity. While for pure Ni the spectrum shows a flat high reflectivity response, those for x ~0.84 and ~0.75 have a Drude component, vibrational modes mostly carrier screened, and a long tail reaching near infrared frequencies. This is asso-ciated with hopping electron conductivity and strong electron-phonon interactions. Small pola-ron fits to the optical conductivity points to SiO2 glass stretching modes as the phonons having the main interacting role. The relative reduction of the number of carriers in Ni0.75(SiO2)0.25 allows less screened phonon bands on the top of a continuum and a wide and overdamped oscillator at mid-infrared frequencies. Ni0.61(SiO2)0.39, with a metal fraction closer to the percolation threshold, undergoes a metal-nonmetal transition at ~77 K. Here, it is suggested by the scattering rate a nearly quad-ratic dependence allowing a broad identification of two relaxation times as due to two carrier contributions associated to a Drude contribution and a mid-infrared overdamped band, respec-tively. Disorder induced, the mid-infrared con-tribution drives the phase transition by thermal electron localization. Ni0.54(SiO2)0.46 and Ni0.28(SiO2)0.72 have well defined vibrational bands and a sharp threshold at ~1450 cm-1 originating in electron promotion, localization, and defects. It is most remarkable a distinctive resonant sharp peak found for p-polarized angle dependent specular reflectivity. It originates in a carrier cloud traced to electrons that are not able to overcome the metal-dielectric interface that, beating against the positive background, generates the electric dipole. At higher oblique angles, this localized nanoplasma couples to SiO2 longitudinal optical Berreman phonons resulting in band peak sof-tening reminiscent to the phonon behavior un-dergoing strong electron-phonon interactions. Singular to a globally insulating phase, we be-lieve that this resonance might be a useful tool for tracking metal-insulator phase transitions in inhomogeneous materials. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. metal-nonmetal transition at ~77 K. Here, it is suggested by the scattering rate a nearly quad-ratic dependence allowing a broad identification of two relaxation times as due to two carrier contributions associated to a Drude contribution and a mid-infrared overdamped band, respec-tively. Disorder induced, the mid-infrared con-tribution drives the phase transition by thermal electron localization. Ni0.54(SiO2)0.46 and Ni0.28(SiO2)0.72 have well defined vibrational bands and a sharp threshold at ~1450 cm-1 originating in electron promotion, localization, and defects. It is most remarkable a distinctive resonant sharp peak found for p-polarized angle dependent specular reflectivity. It originates in a carrier cloud traced to electrons that are not able to overcome the metal-dielectric interface that, beating against the positive background, generates the electric dipole. At higher oblique angles, this localized nanoplasma couples to SiO2 longitudinal optical Berreman phonons resulting in band peak sof-tening reminiscent to the phonon behavior un-dergoing strong electron-phonon interactions. Singular to a globally insulating phase, we be-lieve that this resonance might be a useful tool for tracking metal-insulator phase transitions in inhomogeneous materials. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. Ni0.61(SiO2)0.39, with a metal fraction closer to the percolation threshold, undergoes a metal-nonmetal transition at ~77 K. Here, it is suggested by the scattering rate a nearly quad-ratic dependence allowing a broad identification of two relaxation times as due to two carrier contributions associated to a Drude contribution and a mid-infrared overdamped band, respec-tively. Disorder induced, the mid-infrared con-tribution drives the phase transition by thermal electron localization. Ni0.54(SiO2)0.46 and Ni0.28(SiO2)0.72 have well defined vibrational bands and a sharp threshold at ~1450 cm-1 originating in electron promotion, localization, and defects. It is most remarkable a distinctive resonant sharp peak found for p-polarized angle dependent specular reflectivity. It originates in a carrier cloud traced to electrons that are not able to overcome the metal-dielectric interface that, beating against the positive background, generates the electric dipole. At higher oblique angles, this localized nanoplasma couples to SiO2 longitudinal optical Berreman phonons resulting in band peak sof-tening reminiscent to the phonon behavior un-dergoing strong electron-phonon interactions. Singular to a globally insulating phase, we be-lieve that this resonance might be a useful tool for tracking metal-insulator phase transitions in inhomogeneous materials. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. metal-nonmetal transition at ~77 K. Here, it is suggested by the scattering rate a nearly quad-ratic dependence allowing a broad identification of two relaxation times as due to two carrier contributions associated to a Drude contribution and a mid-infrared overdamped band, respec-tively. Disorder induced, the mid-infrared con-tribution drives the phase transition by thermal electron localization. Ni0.54(SiO2)0.46 and Ni0.28(SiO2)0.72 have well defined vibrational bands and a sharp threshold at ~1450 cm-1 originating in electron promotion, localization, and defects. It is most remarkable a distinctive resonant sharp peak found for p-polarized angle dependent specular reflectivity. It originates in a carrier cloud traced to electrons that are not able to overcome the metal-dielectric interface that, beating against the positive background, generates the electric dipole. At higher oblique angles, this localized nanoplasma couples to SiO2 longitudinal optical Berreman phonons resulting in band peak sof-tening reminiscent to the phonon behavior un-dergoing strong electron-phonon interactions. Singular to a globally insulating phase, we be-lieve that this resonance might be a useful tool for tracking metal-insulator phase transitions in inhomogeneous materials. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. The relative reduction of the number of carriers in Ni0.75(SiO2)0.25 allows less screened phonon bands on the top of a continuum and a wide and overdamped oscillator at mid-infrared frequencies. Ni0.61(SiO2)0.39, with a metal fraction closer to the percolation threshold, undergoes a metal-nonmetal transition at ~77 K. Here, it is suggested by the scattering rate a nearly quad-ratic dependence allowing a broad identification of two relaxation times as due to two carrier contributions associated to a Drude contribution and a mid-infrared overdamped band, respec-tively. Disorder induced, the mid-infrared con-tribution drives the phase transition by thermal electron localization. Ni0.54(SiO2)0.46 and Ni0.28(SiO2)0.72 have well defined vibrational bands and a sharp threshold at ~1450 cm-1 originating in electron promotion, localization, and defects. It is most remarkable a distinctive resonant sharp peak found for p-polarized angle dependent specular reflectivity. It originates in a carrier cloud traced to electrons that are not able to overcome the metal-dielectric interface that, beating against the positive background, generates the electric dipole. At higher oblique angles, this localized nanoplasma couples to SiO2 longitudinal optical Berreman phonons resulting in band peak sof-tening reminiscent to the phonon behavior un-dergoing strong electron-phonon interactions. Singular to a globally insulating phase, we be-lieve that this resonance might be a useful tool for tracking metal-insulator phase transitions in inhomogeneous materials. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. metal-nonmetal transition at ~77 K. Here, it is suggested by the scattering rate a nearly quad-ratic dependence allowing a broad identification of two relaxation times as due to two carrier contributions associated to a Drude contribution and a mid-infrared overdamped band, respec-tively. Disorder induced, the mid-infrared con-tribution drives the phase transition by thermal electron localization. Ni0.54(SiO2)0.46 and Ni0.28(SiO2)0.72 have well defined vibrational bands and a sharp threshold at ~1450 cm-1 originating in electron promotion, localization, and defects. It is most remarkable a distinctive resonant sharp peak found for p-polarized angle dependent specular reflectivity. It originates in a carrier cloud traced to electrons that are not able to overcome the metal-dielectric interface that, beating against the positive background, generates the electric dipole. At higher oblique angles, this localized nanoplasma couples to SiO2 longitudinal optical Berreman phonons resulting in band peak sof-tening reminiscent to the phonon behavior un-dergoing strong electron-phonon interactions. Singular to a globally insulating phase, we be-lieve that this resonance might be a useful tool for tracking metal-insulator phase transitions in inhomogeneous materials. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Science Nucleus Basic and Applied Mag-netism P06-022F, and Fondecyt 1080164 (Chile). N.E.M. acknowledges the Argentinean National Research Council (CONICET)-Project No. PIP 5152/06. Ni0.61(SiO2)0.39, with a metal fraction closer to the percolation threshold, undergoes a metal-nonmetal transition at ~77 K. Here, it is suggested by the scattering rate a nearly quad-ratic dependence allowing a broad identification of two relaxation times as due to two carrier contributions associated to a Drude contribution and a mid-infrared overdamped band, respec-tively. Disorder induced, the mid-infrared con-tribution drives the phase transition by thermal electron localization. Ni0.54(SiO2)0.46 and Ni0.28(SiO2)0.72 have well defined vibrational bands and a sharp threshold at ~1450 cm-1 originating in electron promotion, localization, and defects. It is most remarkable a distinctive resonant sharp peak found for p-polarized angle dependent specular reflectivity. It originates in a carrier cloud traced to electrons that are not able to overcome the metal-dielectric interface that, beating against the positive background, generates the electric dipole. At higher oblique angles, this localized nanoplasma couples to SiO2 longitudinal optical Berreman phonons resulting in band peak sof-tening reminiscent to the phonon behavior un-dergoing strong electron-phonon interactions. Singular to a globally insulating phase, we be-lieve that this resonance might be a useful tool for tracking metal-insulator phase transitions in inhomogeneous materials. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating net-work polarons are formed. We acknowledge partial financial support by the Foundation for Harboring Research of the State of Sao Paulo _Fundação de Amparo dà Pesquisa do Estado de São Paulo-FAPESP_ and by the National Council for Technological and Scientific Development (Conselho Nacional de Desenvolvimento Cientìfico e Tecnológico-CNPq_, Brazil. J.C.D. is grateful to the Millen-nium Scienc
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