  The Cd1-xZnxTe semiconductor alloy is a regular system regarding its
macroscopic mechanic properties in that its experimental bulk modulus exhibits
a linear x-dependence, in line with ab initio predictions. Complexity arises at
the bond scale, referring to the intricate Cd1-xZnxTe percolation-type Raman
pattern [T. Alhaddad et al., Journal of Applied Physics 133, 065701 (2023)].
This offers an appealing benchmark to test various phonon coupling processes at
diverse length scales in a compact multi-oscillator assembly, presently tuned
by pressure. At x around 0, an inter-bond long-range/macro electric coupling
between the matrix and impurity polar phonons is detuned under pressure.
Inversely, at x around 1, an intra-bond short-range/nano mechanic coupling is
enforced between the two Zn Te apolar sub-phonons stemming from same and alien
percolation-type environments. The pressure-induced macro/nano polar/apolar
coupling/decoupling processes are compared within a model of two coupled
electric/mechanic harmonic oscillators in terms of a compromise between
proximity to resonance and strength of coupling, impacting the degree of mode
mixing, with ab initio (apolar case) and analytical (polar case) Raman
calculations in support. Notably, the free mechanic coupling at x around 1
opposes the achievement of a phonon exceptional point, manifesting the
inhibition of mechanic coupling, earlier evidenced with similar bonds for x
smaller than 0.5. Hence, the pressure dependence of a given bond vibration in a
disordered alloy basically differs depending on whether the bond is
matrix-like, i.e., self-connected in bulk (free coupling), or dispersed, i.e.,
self-connected in a chain (inhibited coupling). This features pressure-tunable
percolation-based on-off phonon switches in complex media.
