| Autor: |
Peter Strehlow, S. Hunklinger, Christian Enss |
| Rok vydání: |
1999 |
| Předmět: |
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| Zdroj: |
Physica B: Condensed Matter. :248-252 |
| ISSN: |
0921-4526 |
| DOI: |
10.1016/s0921-4526(98)01349-0 |
| Popis: |
At low temperatures glasses exhibit a variety of surprising properties. They are attributed to the existence of low-energy excitations which are caused by the tunneling of small atomic clusters. With decreasing temperature the interaction between the tunneling systems becomes increasingly important and a transition from a coherent to an incoherent tunneling motion occurs. Very recently a new and unexpected phenomenon was found. Below a critical temperature Tc=5.8 mK the dielectric constant of the multicomponent glass BaO–Al2O3–SiO2 becomes highly sensitive to very weak magnetic fields. In addition, the dielectric constant shows a kink at that temperature. Both observations indicate the occurrence of a phase transition from a state of uncorrelated and incoherent tunneling to a highly correlated motion of a macroscopic number of tunneling systems. Above Tc, the dielectric constant exhibits a maximum at moderate magnetic fields. This dependence vanishes rapidly with increasing temperature. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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Full Text from ScienceDirect