Universität zu Köln

Behnia, Kamran ORCID: 0000-0001-8997-5645 and Kapitulnik, Aharon (2019). A lower bound to the thermal diffusivity of insulators. J. Phys.-Condes. Matter, 31 (40). BRISTOL: IOP PUBLISHING LTD. ISSN 1361-648X

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Abstract

It has been known for decades that thermal conductivity of insulating crystals becomes proportional to the inverse of temperature when the latter is comparable to, or higher than, the Debye temperature. This behavior has been understood as resulting from Umklapp scattering among phonons. We put under scrutiny the magnitude of the thermal diffusion constant in this regime and find that it does not fall below a threshold set by the square of sound velocity times the Planckian time (tau(p) = (h) over bar /k(B)T). The conclusion, based on scrutinizing the ratio in cubic crystals with high thermal resistivity. appears to hold even in glasses where Umklapp events are not conceivable. Explaining this boundary, reminiscent of a recently-noticed limit for charge transport in metals, is a challenge to theory.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Behnia, Kamran UNSPECIFIED orcid.org/0000-0001-8997-5645 UNSPECIFIED Kapitulnik, Aharon UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-131226
DOI:	10.1088/1361-648X/ab2db6
Journal or Publication Title:	J. Phys.-Condes. Matter
Volume:	31
Number:	40
Date:	2019
Publisher:	IOP PUBLISHING LTD
Place of Publication:	BRISTOL
ISSN:	1361-648X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language HEAT-CAPACITY; CONDUCTIVITY; TEMPERATURE; SUPERCONDUCTIVITY; PROPAGATION; ANISOTROPY Multiple languages Physics, Condensed Matter Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/13122