Direct Evidence for a Two-component Tunnelling Mechanism in the Multicomponent Glasses at Low Temperatures

Abstract

The dielectric anomalies of window-type glasses at low temperatures ($T<$ 1 K) are rather successfully explained by the two-level systems (2LS) tunneling model (TM). However, the magnetic effects discovered in the multisilicate glasses in recent times \cite{ref1}-\cite{ref3}, and also some older data from mixed (SiO${}_2$)${}_{1-x}$(K${}_2$O)${}_x$ and (SiO${}_2$)${}_{1-x}$(Na${}_2$O)${}_x$ glasses \cite{ref4}, indicate the need for a suitable generalization of the 2LS TM. We show that, not only for the magnetic effects \cite{ref3,ref5} but also for the mixed glasses in the absence of a field, the right extension of the 2LS TM is provided by the (anomalous) multilevel tunneling systems approach proposed by one of us. It appears that new 2LS develop via dilution near the hull of the SiO${}_4$-percolating clusters in the mixed glasses.

4 pages, 4 figures, submitted for publication

References in corpus (5)

• Channel Formation and Intermediate Range Order in Sodium Silicate Melts and Glasses
• The Intrinsic Quantum Excitations of Low Temperature Glasses
• Dephasing of Atomic Tunneling by Nuclear Quadrupoles
• Magnetic field effect on the dielectric constant of glasses: Evidence of disorder within tunneling barriers
• Multi-Welled Tunneling Model for the Magnetic-Field Effect in Ultracold Glasses

Cited by in corpus (3)

• Realistic Tunneling States for the Magnetic Effects in Non-Metallic Real Glasses
• On the Paramagnetic Impurity Concentration of Silicate Glasses from Low-Temperature Physics
• A new Phenomenon: Glass Paramagnetism. Further Experimental and Theoretical Details