The generic 1-bond:2-mode percolation type Raman signal inherent to the short bond of common (A,B)C semiconductor mixed crystals with zincblende (cubic) structure is exploited as a sensitive mesoscope to explore how various ZnSe-based systems engage their pressure-induced structural transition (to rock-salt) at the sub-macroscopic scale with a focus on ZnCdSe. The Raman doublet, that distinguishes between the AC- and BC-like environments of the short bond, is reactive to pressure: either it closes (ZnBeSe, ZnSeS) or it opens (ZnCdSe), depending on the hardening rates of the two environments under pressure. A partition of II-VI and III-V mixed crystals is accordingly outlined. Of special interest is the closure case, in which the system resonantly stabilizes ante transition at its exceptional point corresponding to a virtual decoupling, by overdamping, of the two oscillators forming the Raman doublet. At this limit, the chain-connected bonds of the short species (taken as the minor one) freeze along the chain into a rigid backbone. This reveals a capacity behind alloying to reduce the thermal conductivity.
@article{arxiv.2008.07187,
title = {Phonon-based partition of (ZnSe-like) semiconductor mixed crystals on approach to their pressure-induced structural transition},
author = {M. B. Shoker and O. Pagès and V. J. B. Torres and A. Polian and J. -P. Itié and G. K. Pradhan and C. Narayana and M. N. Rao and R. Rao and C. Gardiennet and G. Kervern and K. Strzałkowski and F. Firszt},
journal= {arXiv preprint arXiv:2008.07187},
year = {2020}
}