Absence of localization in a random-dimer model

Engineering bands of extended electronic states in a class of topologically disordered and quasiperiodic lattices

“…This happens independent of the energy E of the electron. This result needs to be contrasted clearly with that in the RDM [27] where the local structure of disorder could transform one subset of the transfer matrices into unit matrices, but only at special value of E. In our case, with the commutation condition satisfied one can arrange the constituent elements α and β-γ even in any kind of perfect periodic order. The wave functions as a result, will have to be of a perfectly extended, Bloch-like character and the energy bands will exhibit absolutely continuous measure whenever λ = ± t 2 B − t 2 A .…”

“…This path breaking result was initially put forward by Dunlap et al [27] in connection with a sudden enhancement of conductance of a class of polyanilenes on protonation. Known as the random dimer model (RDM) the phenomenon is attributed to certain special kinds of positional correlation in the potential profiles.…”

Universal scheme to generate metal–insulator transition in disordered systems

“…However, Anderson localization breaks down in the random binary alloy when correlations are introduced in the disorder distribution. A discrete number of extended states have been reported in the random-dimer model [18][19][20] and its generalized versions [21,22], where one or both sites always appear in n-mer. A band of extended states will emerge in the binary alloy when the site energies are long-range correlated [23].…”

“…3(b) we obtain β=−1], due to the Anderson localization effects, although they possess either the diagonal disorder (dashed lines) or the off-diagonal disorder (dotted lines) and are more ordered than the former case. the disorder degree is very large [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], we can see from Fig. 3(c) that ξ L is independent of W for the former ladder and all states are always extended in the gray energy region [ Fig.…”

Coherent electron dynamics in a two-dimensional random system with mobility edges

“…In onedimensional (1D) and two-dimensional (2D) electronic systems with time-reversal symmetry, this theory predicts the absence of a disorder-driven metal-insulator transition for any degree of uncorrelated disorder. Recently, however, it has been reported that the presence of short [4,5,6,7,8,9,10] or long-range correlations [11,12,13,14] in disorder acts towards the appearance of truly delocalized states in 1D Anderson models. This theoretical predictions was put forward to account for transport properties of semiconductor superlattices with intentional short-range correlated disorder [15] and microwave transmission spectra of single-mode waveguides with inserted long-range correlated scatters [16].…”