2008/01/31 by Moshe Schechter, M. Schechter, P. C. E. Stamp
Materials Science · Physics and Astronomy · #Glass properties and applications #Material Dynamics and Properties #Theoretical and Computational Physics #cond-mat.dis-nn
paper · pdf · doi:10.1088/0953-8984/20/24/244136
published as J. Phys.: Condens. Matter 20, 244136 (2008) · 12 pages, 2 figures. Minor modifications, published version
openalex publication_date 2008/05/29 · arxiv created 2008/06/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The form of the low-temperature interactions between defects in neutral glasses is reconsidered. We analyse the case where the defects can be modelled either as simple 2-level tunneling systems, or tunneling rotational impurities. The coupling to strain fields is determined up to 2nd order in the displacement field. It is shown that the linear coupling generates not only the usual 1/r3 Ising-like interaction between the rotational tunneling defect modes, which cause them to freeze around a temperature TG, but also a random field term. At lower temperatures the inversion symmetric tunneling modes are still active - however the coupling of these to the frozen rotational modes, now via the 2nd-order coupling to phonons, generates another random field term acting on the inversion symmetric modes (as well as shorter-range 1/r5 interactions between them). Detailed expressions for all these couplings are given.