Effect of Nuclear Quadrupole Interaction on the Relaxation in Amorphous Solids

Abstract

Recently it has been experimentally demonstrated that certain glasses display an unexpected magnetic field dependence of the dielectric constant. In particular, the echo technique experiments have shown that the echo amplitude depends on the magnetic field. The analysis of these experiments results in the conclusion that the effect seems to be related to the nuclear degrees of freedom of tunneling systems. The interactions of a nuclear quadrupole electrical moment with the crystal field and of a nuclear magnetic moment with magnetic field transform the two-level tunneling systems inherent in amorphous dielectrics into many-level tunneling systems. The fact that these features show up at temperatures $T<100mK$, where the properties of amorphous materials are governed by the long-range $R^{-3}$ interaction between tunneling systems, suggests that this interaction is responsible for the magnetic field dependent relaxation. We have developed a theory of many-body relaxation in an ensemble of interacting many-level tunneling systems and show that the relaxation rate is controlled by the magnetic field. The results obtained correlate with the available experimental data. Our approach strongly supports the idea that the nuclear quadrupole interaction is just the key for understanding the unusual behavior of glasses in a magnetic field.

arXiv comment18 pages, 9 figures

References in corpus (7)

• Evidence for a Second Order Phase Transition in Glasses at Very Low Temperatures -- A Macroscopic Quantum State of Tunneling Systems
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• Correlated Persistent Tunneling Currents in Glasses
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Cited by in corpus (4)

• Effect of nuclear quadrupole interactions on the dynamics of two-level systems in glasses
• On the theory of resonant susceptibility of dielectric glasses in magnetic field
• Low temperature breakdown of coherent tunneling in amorphous solids induced by the nuclear quadrupole interaction
• Dielectric Susceptibility and Heat Capacity of Ultra-Cold Glasses in Magnetic Field