Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7

Autores
Nucara, A.; Mohamed, W. S.; Baldassarre, L.; Koval, Sergio Fabian; Lorenzana, J.; Fittipaldi, R.; Balakrishnan, G.; Vecchione, A.; Calvani, P.
Año de publicación
2014
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
The lattice dynamics of Ba2CuGe2O7, a compound which develops Dzyaloshinsky-Moriya helical magnetism below TN=3.2 K, has been studied by measuring the infrared reflectivity of a single crystal with the radiation polarized both in the ab plane and along the c axis of its tetragonal cell, from 7 to 300 K. In this compound, where the unit cell has no inversion symmetry, 14 E phonon modes of the ab plane, out of the 18 predicted, and nine B2 modes of the c axis, out of the ten predicted, have been observed. They have been assigned to the atomic motions by a comparison with shell-model calculations, which provided vibrational frequencies in good agreement with the experiment, while most calculated intensities turned out to be much lower than the experimental values. This discrepancy has been tentatively explained by assuming strong electron-phonon interactions, a hypothesis supported by the failure of the f-sum rule if restricted to the phonon region. Indeed, we observe a remarkable increase in the oscillator strengths between 300 and 200 K for the phonons of the ab plane (between 300 and 100 K for the c axis), which implies an increase in the dielectric constant of Ba2CuGe2O7 below room temperature.
Fil: Nucara, A.. Universita di Roma “La Sapienza”; Italia
Fil: Mohamed, W. S.. Universita di Roma “La Sapienza”; Italia
Fil: Baldassarre, L.. Istituto Italiano di Tecnologia; Italia
Fil: Koval, Sergio Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina
Fil: Lorenzana, J.. Universita di Roma “La Sapienza”; Italia
Fil: Fittipaldi, R.. Istituto Superconduttori, Materiali Innovativi e Dispositivi; Italia
Fil: Balakrishnan, G.. University Of Warwick; Reino Unido
Fil: Vecchione, A.. Istituto Superconduttori, Materiali Innovativi e Dispositivi; Italia
Fil: Calvani, P.. Universita di Roma “La Sapienza”; Italia
Materia
Lattice Dynamics
Magnetoelectricity
Shell Model
Infrared Spectroscopy
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/6156
Acceder
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oai_identifier_str oai:ri.conicet.gov.ar:11336/6156
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repository_id_str 3498
network_name_str CONICET Digital (CONICET)
spelling Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7Nucara, A.Mohamed, W. S.Baldassarre, L.Koval, Sergio FabianLorenzana, J.Fittipaldi, R.Balakrishnan, G.Vecchione, A.Calvani, P.Lattice DynamicsMagnetoelectricityShell ModelInfrared Spectroscopyhttps://purl.org/becyt/ford/1.3https://purl.org/becyt/ford/1The lattice dynamics of Ba2CuGe2O7, a compound which develops Dzyaloshinsky-Moriya helical magnetism below TN=3.2 K, has been studied by measuring the infrared reflectivity of a single crystal with the radiation polarized both in the ab plane and along the c axis of its tetragonal cell, from 7 to 300 K. In this compound, where the unit cell has no inversion symmetry, 14 E phonon modes of the ab plane, out of the 18 predicted, and nine B2 modes of the c axis, out of the ten predicted, have been observed. They have been assigned to the atomic motions by a comparison with shell-model calculations, which provided vibrational frequencies in good agreement with the experiment, while most calculated intensities turned out to be much lower than the experimental values. This discrepancy has been tentatively explained by assuming strong electron-phonon interactions, a hypothesis supported by the failure of the f-sum rule if restricted to the phonon region. Indeed, we observe a remarkable increase in the oscillator strengths between 300 and 200 K for the phonons of the ab plane (between 300 and 100 K for the c axis), which implies an increase in the dielectric constant of Ba2CuGe2O7 below room temperature.Fil: Nucara, A.. Universita di Roma “La Sapienza”; ItaliaFil: Mohamed, W. S.. Universita di Roma “La Sapienza”; ItaliaFil: Baldassarre, L.. Istituto Italiano di Tecnologia; ItaliaFil: Koval, Sergio Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Lorenzana, J.. Universita di Roma “La Sapienza”; ItaliaFil: Fittipaldi, R.. Istituto Superconduttori, Materiali Innovativi e Dispositivi; ItaliaFil: Balakrishnan, G.. University Of Warwick; Reino UnidoFil: Vecchione, A.. Istituto Superconduttori, Materiali Innovativi e Dispositivi; ItaliaFil: Calvani, P.. Universita di Roma “La Sapienza”; ItaliaAmerican Physical Society2014-07info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/6156Nucara, A.; Mohamed, W. S.; Baldassarre, L.; Koval, Sergio Fabian; Lorenzana, J.; et al.; Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7; American Physical Society; Physical Review B; 90; 1; 7-2014; 14304-143040163-1829enginfo:eu-repo/semantics/altIdentifier/url/http://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.014304info:eu-repo/semantics/altIdentifier/doi/info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevB.90.014304info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-29T10:36:00Zoai:ri.conicet.gov.ar:11336/6156instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-09-29 10:36:00.731CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7
title Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7
spellingShingle Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7
Nucara, A.
Lattice Dynamics
Magnetoelectricity
Shell Model
Infrared Spectroscopy
title_short Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7
title_full Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7
title_fullStr Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7
title_full_unstemmed Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7
title_sort Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7
dc.creator.none.fl_str_mv Nucara, A.
Mohamed, W. S.
Baldassarre, L.
Koval, Sergio Fabian
Lorenzana, J.
Fittipaldi, R.
Balakrishnan, G.
Vecchione, A.
Calvani, P.
author Nucara, A.
author_facet Nucara, A.
Mohamed, W. S.
Baldassarre, L.
Koval, Sergio Fabian
Lorenzana, J.
Fittipaldi, R.
Balakrishnan, G.
Vecchione, A.
Calvani, P.
author_role author
author2 Mohamed, W. S.
Baldassarre, L.
Koval, Sergio Fabian
Lorenzana, J.
Fittipaldi, R.
Balakrishnan, G.
Vecchione, A.
Calvani, P.
author2_role author
author
author
author
author
author
author
author
dc.subject.none.fl_str_mv Lattice Dynamics
Magnetoelectricity
Shell Model
Infrared Spectroscopy
topic Lattice Dynamics
Magnetoelectricity
Shell Model
Infrared Spectroscopy
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.3
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv The lattice dynamics of Ba2CuGe2O7, a compound which develops Dzyaloshinsky-Moriya helical magnetism below TN=3.2 K, has been studied by measuring the infrared reflectivity of a single crystal with the radiation polarized both in the ab plane and along the c axis of its tetragonal cell, from 7 to 300 K. In this compound, where the unit cell has no inversion symmetry, 14 E phonon modes of the ab plane, out of the 18 predicted, and nine B2 modes of the c axis, out of the ten predicted, have been observed. They have been assigned to the atomic motions by a comparison with shell-model calculations, which provided vibrational frequencies in good agreement with the experiment, while most calculated intensities turned out to be much lower than the experimental values. This discrepancy has been tentatively explained by assuming strong electron-phonon interactions, a hypothesis supported by the failure of the f-sum rule if restricted to the phonon region. Indeed, we observe a remarkable increase in the oscillator strengths between 300 and 200 K for the phonons of the ab plane (between 300 and 100 K for the c axis), which implies an increase in the dielectric constant of Ba2CuGe2O7 below room temperature.
Fil: Nucara, A.. Universita di Roma “La Sapienza”; Italia
Fil: Mohamed, W. S.. Universita di Roma “La Sapienza”; Italia
Fil: Baldassarre, L.. Istituto Italiano di Tecnologia; Italia
Fil: Koval, Sergio Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina
Fil: Lorenzana, J.. Universita di Roma “La Sapienza”; Italia
Fil: Fittipaldi, R.. Istituto Superconduttori, Materiali Innovativi e Dispositivi; Italia
Fil: Balakrishnan, G.. University Of Warwick; Reino Unido
Fil: Vecchione, A.. Istituto Superconduttori, Materiali Innovativi e Dispositivi; Italia
Fil: Calvani, P.. Universita di Roma “La Sapienza”; Italia
description The lattice dynamics of Ba2CuGe2O7, a compound which develops Dzyaloshinsky-Moriya helical magnetism below TN=3.2 K, has been studied by measuring the infrared reflectivity of a single crystal with the radiation polarized both in the ab plane and along the c axis of its tetragonal cell, from 7 to 300 K. In this compound, where the unit cell has no inversion symmetry, 14 E phonon modes of the ab plane, out of the 18 predicted, and nine B2 modes of the c axis, out of the ten predicted, have been observed. They have been assigned to the atomic motions by a comparison with shell-model calculations, which provided vibrational frequencies in good agreement with the experiment, while most calculated intensities turned out to be much lower than the experimental values. This discrepancy has been tentatively explained by assuming strong electron-phonon interactions, a hypothesis supported by the failure of the f-sum rule if restricted to the phonon region. Indeed, we observe a remarkable increase in the oscillator strengths between 300 and 200 K for the phonons of the ab plane (between 300 and 100 K for the c axis), which implies an increase in the dielectric constant of Ba2CuGe2O7 below room temperature.
publishDate 2014
dc.date.none.fl_str_mv 2014-07
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/6156
Nucara, A.; Mohamed, W. S.; Baldassarre, L.; Koval, Sergio Fabian; Lorenzana, J.; et al.; Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7; American Physical Society; Physical Review B; 90; 1; 7-2014; 14304-14304
0163-1829
url http://hdl.handle.net/11336/6156
identifier_str_mv Nucara, A.; Mohamed, W. S.; Baldassarre, L.; Koval, Sergio Fabian; Lorenzana, J.; et al.; Infrared phonon spectrum of the tetragonal helimagnet Ba2CuGe2O7; American Physical Society; Physical Review B; 90; 1; 7-2014; 14304-14304
0163-1829
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/url/http://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.014304
info:eu-repo/semantics/altIdentifier/doi/
info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevB.90.014304
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv American Physical Society
publisher.none.fl_str_mv American Physical Society
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
collection CONICET Digital (CONICET)
instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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score 13.070432

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