Defects&TLSs and glass transition
theory
- KT transition as a reason for non-Arrhenius behaviour?
2022 Theory of melting of glasses Chandra M. Varma
motivation - specific heat peak at melting temperature is closely connected with the density of LEEs see also as linear-in-temperature specific heat at VERY low temperatures. Therefore LEAKING (with or without tunneling). Both phenomena, peak at $T_g$ and $\gamma*T$ of specific heat at glass temperature and low tempreatures correspondingly, occur concurrently
- 2019 Nussinov-Weingarter
already topological-KT transition
Third, the measured $T^3$ specific heat is larger than that given by the elastic constants - the original TLM has nothing to say about this.
The change in the so called excess $T^3$ specific heat with density is identical to that of the linear in T heat capacity
HUGE peak for crystal but noticeable peak for glass - features of the specific heat
open questions
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a) since $T_G \sim 100-1000K$, for defect-freezing-out transition the defect size needs to be $\xi_G \sim 10A=10^{-7}cm$
1-order of magnitude ---BPeak energy scale of defect is (30k), but glass temperature (300k)
crossover temparature $T_Q \sim 10K$ is by KT relation $T_Q \approx \frac{1}{2} \rho_s \sim \frac{\gamma^2}{\rho c_t^2 \xi^3}$
$10K \sim 10^{-15} erg \sim 10^{-3} eV \sim \frac{\hbar c}{R_0}$
$10^{-15} erg = \frac{10^{-27} erg*s *4*10^5 cm/s}{50 A}$, so $R_0 \sim 50A$
IF $\gamma \sim 6.3eV$ and $\rho c_t^2 \xi^3 \approx 2(g/cm^3) 4^2 10^{10} (cm/s)^2 125*10^{-21} cm^3 \approx 4*10^{-8} erg=40,000eV$,
so $T_Q \sim 10^{-3} eV \sim 10K$
- b) RG equations to be checked/reproduced?
2022 Anomalous Elasticity and Emergent Dipole Screening in Three-Dimensional Amorphous Solids
experimental links - forcing out of "universal"/natural regime
- 2015 Two-Level Systems in Evaporated Amorphous Silicon D.R. Queen, X. Liu, J. Karel, H.C. Jacks, T.H. Metcalf, F. Hellman
- 2014 Suppression of tunneling two-level systems in ultrastable glasses of indomethacin Tomás Pérez-Castañeda, Cristian Rodríguez-Tinoco, Javier Rodríguez-Viejo, and Miguel A. Ramos
experiments around "universal regime"
How Universal are the Low Temperature Acoustic Properties of Glasses? - 1988 - Berret-Meissner