Nanoscales - Shukla

https://arxiv.org/search/cond-mat?searchtype=author&query=Shukla%2C+P

2021 Universality of Ultrasonic attenuation in amorphous systems at low temperatures - Pragya Shukla

Based on experimental evidence of ordered structure in glasses below MRO (10 → 30˚A) and its lack above, we describe a macroscopic size glass material as elastically coupled, spherical shape, generic blocks, with homogeneous dispersion interaction within each such block.

Low temperature Universalities in amorphous systems: role of microscopic length scales

For amorphous systems, the length scale is of the medium range topological orders and its ratio with the distance of closest approach between molecules turns out to be a constant.

The above length scales are also related to Ioffe-Regel frequency and boson peak frequency of the vibrational spectrum
and indicate that the former is of the same order as the latter for transverse phonon-dynamics

... The approach in [21] however is based on phonon mediated interactions of generic blocks only, does not take into account the role of interactions within a block and as a consequence, does not explain the physical origin of MB universality. This motivates us to pursue the present work which indicates the origin to lie in a competition between dispersion interactions and phonon mediated coupling between molecules

2021 Boson peak in amorphous systems: role of phonon mediated coupling of nano-clusters

We also find that the copuling between the blocks has no significant effect on the VDOS in the edge of the spectrum and it retains the same approximate Airy functional form as that of a single basic block. Beyond a certain energy scale (of the order of Ioffe-Regel frequency), however phonon DOS becomes significant, resulting in a small flat region for a small energy range and thereafter dominating
the DOS.