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  4. Transporttheorie für geordnete und ungeordnete Systeme schwerer Fermionen
 
Zitierlink URN
https://nbn-resolving.de/urn:nbn:de:gbv:46-diss000112248

Transporttheorie für geordnete und ungeordnete Systeme schwerer Fermionen

Veröffentlichungsdatum
2008-09-02
Autoren
Grenzebach, Claas  
Betreuer
Czycholl, Gerd  
Gutachter
Pruschke, Thomas  
Zusammenfassung
Heavy-fermion systems (HFS, several lanthanide or actinide compounds) exhibit a linear coefficient of the low-temperature specific heat that is much larger than in usual metals, and this enhancement is usually attributed to quasiparticles with a very large effective mass. The essential features of HFS are based on the interplay of localised, strongly correlated f electrons with broad conduction bands as described by the periodic Anderson model (PAM). We investigate the temperature dependence of the transport properties of HFS (e.g. resistivity, thermoelectric power) in the linear-response regime (using Kubo formulae and the Jonson-Mahan theorem).In the dynamical mean-field theory (DMFT), the PAM is mapped on an effective single-impurity model. As impurity solvers we use both Wilson's numerical renormalization group and the modified perturbation theory. In addition, we explore the influence of substitutional disorder on the transport properties of HFS by an extension of the DMFT to a coherent-potential approximation for disordered strongly-correlated electron systems (PAM with random potentials). The typical experimental results are reproduced, in particular the temperature and concentration dependence of the resistivity and the thermoelectric power and their absolute magnitude for both metallic HFS and Kondo insulators.Finally, we examine four different estimates for possible characteristic low-temperature scales of the PAM without disorder. The results indicate that there is only one relevant scale; we get a one-parameter scaling of thermodynamic and some transport properties with a strongly occupancy-dependent scaling function.Also published by Mensch-und-Buch-Verlag Berlin 2008, ISBN 978-3-86664-504-2.See also corresponding articles:DOI 10.1103/PhysRevB.74.195119DOI 10.1103/PhysRevB.77.115125
Schlagwörter
heavy-fermion systems

; 

periodic Anderson model

; 

substitutional disorder

; 

NRG

; 

MPT

; 

DMFT

; 

CPA

; 

linear response

; 

resistivity

; 

thermoelectric power

; 

low-temperature scales
Institution
Universität Bremen  
Fachbereich
Fachbereich 01: Physik/Elektrotechnik (FB 01)  
Dokumenttyp
Dissertation
Zweitveröffentlichung
Nein
Sprache
Deutsch
Dateien
Lade...
Vorschaubild
Name

00011224.pdf

Size

3.44 MB

Format

Adobe PDF

Checksum

(MD5):fc07a8dd0b4c691798b0efb77d230e8c

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