Ruthenium oxide peculiarities probed by Seebeck effect ; Particularités des oxydes de ruthénium sondées par l'effet Seebeck

This thesis deals with the synthesis, the structural study and the magnetic properties and electronic transport studies of different ruthenium oxide families, presenting various magnetic and electronic behaviors, with rutile, R-type hexaferrite and hollandite structures. The goal of this thesis was the study of the ruthenium oxide peculiarities probed by the Seebeck effect in the following materials: RuO2 rutile (edge-shared RuO6 chain interconnected by their vertices) with Boltzmann type transport dominated by electron-phonon interactions, BaCo2Ru4O11 et BaMn2Ru4O11 R-type hexaferrites (edge-... Mehr ...

Verfasser: Pawula, Florent
Dokumenttyp: doctoralThesis
Erscheinungsdatum: 2018
Verlag/Hrsg.: HAL CCSD
Schlagwörter: Ruthenium oxides / RuO2 / Rutile / R-type hexaferrite / Hollandite / Magnetic properties / Magnetoresistance / Electronic transport / Thermopower / Seebeck coefficient / Heikes formula / Spin entropy / Oxyde de ruthénium / Hexaferrite de type R / Transport électronique / Pouvoir thermoélectrique / Coefficient Seebeck / Formule de Heikes / Entropie de spin / [PHYS.PHYS]Physics [physics]/Physics [physics]
Sprache: Französisch
Permalink: https://search.fid-benelux.de/Record/base-27103917
Datenquelle: BASE; Originalkatalog
Powered By: BASE
Link(s) : https://theses.hal.science/tel-02093471

This thesis deals with the synthesis, the structural study and the magnetic properties and electronic transport studies of different ruthenium oxide families, presenting various magnetic and electronic behaviors, with rutile, R-type hexaferrite and hollandite structures. The goal of this thesis was the study of the ruthenium oxide peculiarities probed by the Seebeck effect in the following materials: RuO2 rutile (edge-shared RuO6 chain interconnected by their vertices) with Boltzmann type transport dominated by electron-phonon interactions, BaCo2Ru4O11 et BaMn2Ru4O11 R-type hexaferrites (edge-shared RuO6 octahedra, forming kagome planes, and face-shared RuO6 octahedra) soft ferromagnetic bad metals, and two new hollandites Sr1.5Ru6.1Cr1.9O16 et Ba1.5Ru6.1Cr1.9O16 (double chains of edge-shared RuO6 octahedra, interconnected by their vertices) with localized transport and cluster-glass behavior. The synthesis of both new hollandites by solid state reaction allowed us to show the existence of negative magnetoresistance in this compound family. This thesis shows that the behavior of the Seebeck coefficient of ruthenium oxides with structures mainly consisting of edge-shared RuO6 octahedra presents two different behaviors. At low T, S strongly depends on the crystallographic structure and on the associated electronic structure. On the other hand, in the high T limit, S tends a common value independently of the structure as reported here for the R-type hexaferrites and the hollandites and as previously observed in the ferromagnetic metal SrRuO3 perovskite (apex-shared RuO6 octahedra) and in the metallic with Pauli-type magnetism quadruple perovskite LaCu3Ru4O12 (apex-shared RuO6 octahedra). In these R-type hexaferrites BaCo2Ru4O11 and BaMn2Ru4O11 and these two new hollandites Sr1.5Ru6.1Cr1.9O16 and Ba1.5Ru6.1Cr1.9O16, the high temperature Seebeck coefficient reaches a value dominated by the Ru spin entropy term. ; Dans son ensemble, cette thèse porte sur la synthèse, l’étude structurale et l’étude des propriétés ...