Dynamics of photoexcited quasiparticles in heavy electron compounds

Autoren

Jure Demsar
John L Sarrao
Antoinette J Taylor

DOI

10.1088/0953-8984/18/16/r01

eISSN

1361-648X

ISSN

0953-8984

Ausgabe der Veröffentlichung

16

Zeitschrift

Journal of Physics: Condensed Matter

Online publication date

2006

Paginierung

R281 - R314

Datum der Veröffentlichung

2006

Status

Published

Herausgeber

IOP Publishing

Herausgeber URL

http://dx.doi.org/10.1088/0953-8984/18/16/r01

Datum der Datenerfassung

2020

Titel

Dynamics of photoexcited quasiparticles in heavy electron compounds

Ausgabe der Zeitschrift

18

Data source: Crossref

Abstract

Femtosecond real-time spectroscopy is an emerging new tool for studying low energy electronic structure in correlated electron systems. Motivated by recent advances in understanding the nature of relaxation phenomena in various correlated electron systems (superconductors, density wave systems) the technique has been applied to heavy electron compounds in comparison with their non-magnetic counterparts. While the dynamics in their non-magnetic analogues are similar to the dynamics observed in noble metals (only weak temperature dependences are observed) and can be treated with a simple two-temperature model, the photoexcited carrier dynamics in heavy electron systems show dramatic changes as a function of temperature and excitation level. In particular, below some characteristic temperature the relaxation rate starts to decrease, dropping by more than two orders of magnitude upon cooling down to liquid He temperatures. This behaviour has been consistently observed in various heavy fermion metals as well as Kondo insulators, and is believed to be quite general. In order to account for the experimental observations, two theoretical models have been proposed. The first treats the heavy electron systems as simple metals with very flat electron dispersion near the Fermi level. An electron-phonon thermalization scenario can account for the observed slowing down of the relaxation provided that there exists a mechanism for suppression of electron-phonon scattering when both the initial and final electronic states lie in the region of flat dispersion. An alternative scenario argues that the relaxation dynamics in heavy electron systems are governed by the Rothwarf-Taylor bottleneck, where the dynamics are governed by the presence of a narrow gap in the density of states near the Fermi level. The so-called hybridization gap results from hybridization between localized moments and the conduction electron background. Remarkable agreement with the model suggests that carrier relaxation in a broad class of heavy electron systems (both metals and insulators) is governed by the presence of a (weakly temperature dependent) indirect hybridization gap. Here we review the experimental results on a variety of heavy electron compounds, point out the common features as well as the peculiarities observed in some compounds, and compare the data with existing theoretical models.

Addresses

Jozef Stefan Institute, Jamova 39, SI-1000, Ljubljana, Slovenia.

Autoren

Jure Demsar
John L Sarrao
Antoinette J Taylor

DOI

10.1088/0953-8984/18/16/r01

eISSN

1361-648X

Externe Identifier

PubMed Identifier: 21690740

Open access

false

ISSN

0953-8984

Ausgabe der Veröffentlichung

16

Zeitschrift

Journal of physics. Condensed matter : an Institute of Physics journal

Sprache

eng

Medium

Print-Electronic

Online publication date

2006

Paginierung

R281 - R314

Datum der Veröffentlichung

2006

Status

Published

Datum der Datenerfassung

2011

Titel

Dynamics of photoexcited quasiparticles in heavy electron compounds.

Sub types

Journal Article

Ausgabe der Zeitschrift

18

Data source: Europe PubMed Central

Abstract

Femtosecond real-time spectroscopy is an emerging new tool for studying low energy electronic structure in correlated electron systems. Motivated by recent advances in understanding the nature of relaxation phenomena in various correlated electron systems (superconductors, density wave systems) the technique has been applied to heavy electron compounds in comparison with their non-magnetic counterparts. While the dynamics in their non-magnetic analogues are similar to the dynamics observed in noble metals (only weak temperature dependences are observed) and can be treated with a simple two-temperature model, the photoexcited carrier dynamics in heavy electron systems show dramatic changes as a function of temperature and excitation level. In particular, below some characteristic temperature the relaxation rate starts to decrease, dropping by more than two orders of magnitude upon cooling down to liquid He temperatures. This behaviour has been consistently observed in various heavy fermion metals as well as Kondo insulators, and is believed to be quite general. In order to account for the experimental observations, two theoretical models have been proposed. The first treats the heavy electron systems as simple metals with very flat electron dispersion near the Fermi level. An electron-phonon thermalization scenario can account for the observed slowing down of the relaxation provided that there exists a mechanism for suppression of electron-phonon scattering when both the initial and final electronic states lie in the region of flat dispersion. An alternative scenario argues that the relaxation dynamics in heavy electron systems are governed by the Rothwarf-Taylor bottleneck, where the dynamics are governed by the presence of a narrow gap in the density of states near the Fermi level. The so-called hybridization gap results from hybridization between localized moments and the conduction electron background. Remarkable agreement with the model suggests that carrier relaxation in a broad class of heavy electron systems (both metals and insulators) is governed by the presence of a (weakly temperature dependent) indirect hybridization gap. Here we review the experimental results on a variety of heavy electron compounds, point out the common features as well as the peculiarities observed in some compounds, and compare the data with existing theoretical models.

Autoren

Jure Demsar
John L Sarrao
Antoinette J Taylor

Autoren-URL

https://www.ncbi.nlm.nih.gov/pubmed/21690740

DOI

10.1088/0953-8984/18/16/R01

ISSN

0953-8984

Ausgabe der Veröffentlichung

16

Zeitschrift

J Phys Condens Matter

Sprache

eng

Country

England

Paginierung

R281 - R314

PII

S0953-8984(06)75574-6

Datum der Veröffentlichung

2006

Status

Published

Datum, an dem der Datensatz öffentlich gemacht wurde

2012

Titel

Dynamics of photoexcited quasiparticles in heavy electron compounds.

Sub types

Journal Article

Ausgabe der Zeitschrift

18

Data source: PubMed

Dynamics of photoexcited quasiparticles in heavy electron compounds

Tools