Study of the ferroelectric phase transition in germanium telluride using time-domain terahertz spectroscopy

Kód výsledku v IS VaVaI

RIV/68378271:_____/11:00373848 - isvavai.cz

Výsledek na webu

http://dx.doi.org/10.1103/PhysRevB.84.205209

DOI - Digital Object Identifier

10.1103/PhysRevB.84.205209

Jazyk výsledku

angličtina

Název v původním jazyce

Study of the ferroelectric phase transition in germanium telluride using time-domain terahertz spectroscopy

Popis výsledku v původním jazyce

Germanium telluride is a material presenting both spontaneous polarization and electrical conductivity; the mechanism of its ferroelectric phase transition is still not well understood. While, for a long time, the transition was believed to be of displacive character, recent evidence suggests an order-disorder type. We report results of high-temperature measurements of GeTe thin ?lms by means of terahertz spectroscopy showing the absence of critical phonon softening and revealing a low-frequency excitation in the paraelectric phase. We suggest two possible mechanisms which could be at the origin of this feature: either a critical relaxation related to the phase transition or hopping of free charge carriers. The former mechanism appears more probable due to the observed temperature evolution of the spectra. This indicates a mixed character of the phase transition; assuming a Curie-Weiss behavior, we deduce the value of the Curie-Weiss constant as C 1 105 K.

Název v anglickém jazyce

Study of the ferroelectric phase transition in germanium telluride using time-domain terahertz spectroscopy

Popis výsledku anglicky

Germanium telluride is a material presenting both spontaneous polarization and electrical conductivity; the mechanism of its ferroelectric phase transition is still not well understood. While, for a long time, the transition was believed to be of displacive character, recent evidence suggests an order-disorder type. We report results of high-temperature measurements of GeTe thin ?lms by means of terahertz spectroscopy showing the absence of critical phonon softening and revealing a low-frequency excitation in the paraelectric phase. We suggest two possible mechanisms which could be at the origin of this feature: either a critical relaxation related to the phase transition or hopping of free charge carriers. The former mechanism appears more probable due to the observed temperature evolution of the spectra. This indicates a mixed character of the phase transition; assuming a Curie-Weiss behavior, we deduce the value of the Curie-Weiss constant as C 1 105 K.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

BM - Fyzika pevných látek a magnetismus

OECD FORD obor

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Projekt

GC202/09/J045: Elektronový transport v materiálech vykazujících změny fáze

Návaznosti

Z - Vyzkumny zamer (s odkazem do CEZ)

Rok uplatnění

2011

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Physical Review. B

ISSN

1098-0121

e-ISSN

—

Svazek periodika

84

Číslo periodika v rámci svazku

20

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

8

Strana od-do

"205209/1"-"205209/8"

Kód UT WoS článku

000297104700011

EID výsledku v databázi Scopus

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