Interaction of two level systems in amorphous materials with arbitrary phonon fields

Abstract

To describe the interaction of the two level systems (TLSs) of an amorphous solid with arbitrary strain fields, we introduce a generalization of the standard interaction Hamiltonian. In this new model, the interaction strength depends on the orientation of the TLS with respect to the strain field through a $6\times 6$ symmetric tensor of deformation potential parameters, $[R]$. Taking into account the isotropy of the amorphous solid, we deduce that $[R]$ has only two independent parameters. We show how these two parameters can be calculated from experimental data and we prove that for any amorphous bulk material the average coupling of TLSs with longitudinal phonons is always stronger than the average coupling with transversal phonons (in standard notations, ${\gamma }_l>{\gamma }_t$).

7 pages and 1 figure

References in corpus (2)

• Opportunities for mesoscopics in thermometry and refrigeration: Physics and applications
• Heat transport in ultra-thin dielectric membranes and bridges

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