Low-temperature specific heat of rare-earth-doped silicate glasses
| Autor: | Silvia Völker, Th. Schmidt, H. B. Brom, J. Baak, D. A. van de Straat |
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| Rok vydání: | 1996 |
| Předmět: | |
| Zdroj: | Physical Review B : Condensed Matter, 53(5), 2179-2182 |
| ISSN: | 1095-3795 0163-1829 |
| DOI: | 10.1103/physrevb.53.2179 |
| Popis: | The specific heat ${\mathit{C}}_{\mathit{v}}$ of ${\mathrm{Pr}}^{3+}$- and ${\mathrm{Eu}}^{3+}$-doped silicate glasses has been determined between 0.1 and 10 K. Below about 5 K, ${\mathit{C}}_{\mathit{v}}$\ensuremath{\propto}${\mathit{T}}^{1+\ensuremath{\nu}}$ with \ensuremath{\nu}=0.0\char21{}0.3. This dependence is characteristic for the two-level-system (TLS) contribution to the specific heat, ${\mathit{C}}_{\mathit{v}}^{\mathrm{TLS}}$. The values of ${\mathit{C}}_{\mathit{v}}^{\mathrm{TLS}}$ and \ensuremath{\nu} noticeably vary with the chemical nature and the concentration of the glass modifiers. The number of TLS in samples of almost identical composition is significantly larger for the ${\mathrm{Pr}}^{3+}$ doped than for the ${\mathrm{Eu}}^{3+}$ doped and the undoped glass. Above 5 K, the ${\mathit{T}}^{3}$-phonon term and the ${\mathit{T}}^{5}$ term associated with soft localized vibrations also contribute to ${\mathit{C}}_{\mathit{v}}$. The results do not point to a correlation between the ${\mathit{T}}^{1+\ensuremath{\nu}}$ and the higher-order terms. \textcopyright{} 1996 The American Physical Society. |
| Databáze: | OpenAIRE |
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