Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 0808.1154

Elastic flexibility, fast-ion conduction, boson and floppy modes in AgPO3-AgI glasses examined in Raman scattering, IR reflectance, MDSC, ac electrical conductivity and molar volume experiments

Deassy I. Novita·P. Boolchand·Mohammed Malki·Matthieu Micoulaut
View original source ↗Read source document ↗Export metadata ↓

Abstract

Raman scattering, IR reflectance and modulated DSC measurements are performed on specifically prepared dry (AgI)x(AgPO3)1-x glasses over a wide range of compositions 0 < x < 0.60. A reversibility window is observed in the 0.095< x < 0.378 range, which fixes the elastically rigid but unstressed regime also known as the Intermediate Phase. Glass compositions at x < 0.095 are stressed-rigid, while those at x > 0.378 elastically flexible. Raman optical elasticity power-laws, trends in the nature of the glass transition endotherms corroborate the three elastic phase assignments. Ionic conductivities reveal a step-like increase when glasses become stress-free at x > xc(1) = 0.095, and a logarithmic increase in conductivity (sigma ~ (x-xc(2)t) once they become flexible at x > xc(2) = 0.378 with a power-law t = 1.78. The power-law is consistent with percolation of 3D filamentary conduction pathways. Traces of water doping lower Tg and narrow the reversibility window, and can also completely collapse it. Ideas on network flexibility promoting ion-conduction are in harmony with the unified approach of Ingram et al., who have emphasized the similarity of process compliance or elasticity relating to ion-transport and structural relaxation in decoupled systems. Boson mode frequency and scattering strength display thresholds that coincide with the two elastic phase boundaries. In particular, the scattering strength of the boson mode increases almost linearly with glass composition x, with a slope that tracks the floppy mode fraction as a function of mean coordination number r predicted by mean-field rigidity theory. These data suggest that the excess low frequency vibrations contributing to boson mode in flexible glasses come largely from floppy modes.

Explore related subjects

cond-mat.dis-nn

Keep this discovery

BibTeXRIS

Deassy I. Novita, P. Boolchand, Mohammed Malki, Matthieu Micoulaut. 2008-08-08. Elastic flexibility, fast-ion conduction, boson and floppy modes in AgPO3-AgI glasses examined in Raman scattering, IR reflectance, MDSC, ac electrical conductivity and molar volume experiments. https://arxiv.org/abs/0808.1154

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Irrationality Measure Controls Long-Wavelength Charge Fluctuations in Quasiperiodic Systems

Quasiperiodic order is characterized by irrational frequencies whose rational approximability known as irrationality measure defines distinct arithmetic classes. We establish that this arithmetic classification has direct physical consequences for long-wavelength charge fluctuations. In translation-covariant quasiperiodic systems, the infrared scaling of charge fluctuation is governed by the interplay between the irrationality exponent of irrational frequency and the large-harmonic decay of the hull charge profile: the latter determines the available charge weight, while the former controls how efficiently that weight is transferred to the infrared. Consequently, all algebraic irrational frequencies share the same arithmetic scaling, whereas exceptionally well-approximable transcendental frequencies can exhibit strongly enhanced infrared fluctuation scaling. We further prove that occupied states separated from the Fermi level by a gap stable throughout the hull contribute only an analytic infrared background, leaving the nontrivial scaling to near-Fermi states. Our results extend to general translation-covariant multi-frequency quasiperiodic systems.

cond-mat.dis-nn↗
arXiv2026

Curvature-Induced Geometric Universality in Non-Hermitian Anderson Transitions

In Euclidean space, universality classes of Anderson transitions are primarily determined by symmetry and spatial dimensionality. Here, we present evidence for a geometry-controlled universality class of non-Hermitian Anderson transitions on hyperbolic-like lattices. In this setting, critical behavior is influenced by the large-scale hyperbolic geometry, characterized by negative curvature, exponential volume growth, and a non-Euclidean notion of spatial scaling. Finite-size scaling of participation ratios across several distinct \( \{p,q\} \) tilings reveals one-parameter scaling collapses with a common critical exponent \( \nu\simeq1 \) within numerical accuracy. A complementary phenomenological coarse-grained Landau-Ginzburg analysis shows how exponential correlation-volume growth suppresses critical fluctuations, offering a rationale for the observed mean-field-like scaling. Our results suggest that spatial curvature can act as an additional organizing principle for Anderson-transition universality beyond the conventional dimensionality- and symmetry-based classification.

cond-mat.dis-nn↗
arXiv2026

Finite-rank multiplicative perturbations of rotationally invariant non-Hermitian random matrices

We study finite-rank multiplicative deformations of rotationally invariant non-Hermitian random matrices. More precisely, we consider models of the form $\mathbf{A}(\mathbf{I}+\mathbf{T})$, where $\mathbf{A}$ is a large rotationally invariant non-Hermitian random matrix, $\mathbf{T}$ is a finite-rank normal perturbation, and $\mathbf{I}$ denotes the identity matrix. We characterize the emergence of outlier eigenvalues, their fluctuations, and the associated eigenvector overlaps. Our results provide a multiplicative non-Hermitian counterpart to the classical Baik--Ben Arous--P\'ech\'e framework.

cond-mat.dis-nn↗