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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:22 |
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Conference: Bucharest University Faculty of Physics 2013 Meeting
Section: Solid State Physics and Materials Science
Title:
The interaction of two-level systems with phonons in an amended Soft Potential Model
Authors:
Irina Mihaela Dumitru (1,2), Dragos-Victor Anghel (2), George Alexandru Nemnes (1,2)
Affiliation:
(1) Faclulatea de Fizica, Universitatea Bucuresti
(2) Institutul National de Fizica si Inginerie Nucleara -- "Horia Hulubei"
E-mail
irina.dumitru@theory.nipne.ro
Keywords:
glassy materials, two-level systems (TLS), TLS-phonon coupling
Abstract:
The low temperature properties of amorphous solids are qualitatively different from those of crystals. This difference is due to the existence in the amorphous solids of dynamical defects - atoms or groups of atoms that tunnel from one minimum energy configuration to another - which are modeled by an ensemble of two-level systems (TLS). The exact nature of the TLSs is not known and to describe their interaction with other quasiparticles, like phonons, one has to rely on phenomenological models and general assumptions. Nevertheless, the known models fail to describe the properties of anisotropic solids and mesoscopic objects. Here we present a new model which allows us to calculate the couplings of the TLSs with the phonons in any type of system. Moreover, by our calculations we verify the general phenomenological assumptions made in the older models and amend them.
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