Deformations of charge-density wave crystals under electric field

High-frequency, 'quantum' and electromechanical effects in quasi-one-dimensional charge density wave conductors

“…Such an effect was observed in a number of CDW conductors: TaS 3 , TaSe 4 2 I, K 0X3 MoO 3 , and NbS 3 (phase II) [54,56]. Dependences of the torsion angle on the electric field, jE , measured at different E variation rates give evidence of two contributions [56]: (1) slow Ð threshold, hysteretic (see Section 4.4, Fig. 17b, dark curve), and (2) fast Ð practically linear in terms of voltage.…”

“…In the case of`slow' torsion, shear strain normalized to electric field amounts to 10 À6 m V À1 (at least three orders of magnitude higher than the maximum values of piezomoduli in piezoelectrics). For TaS 3 , the time of switchover between metastable strain states after the application of an electric field higher than the threshold one lies in the range 10 À2 À10 À1 s at liquid-nitrogen temperature and varies approximately as exp 900aT K between 70 and 100 K [56]. Notice that the activation energy equal to 900 K is close to the half-width of the Peierls gap.…”

“…It was revealed that the free end of the sample in the Peierls state turned as the current was passed through metal chains, with the direction of the turn determined by current direction [54]. Such an effect was observed in a number of CDW conductors: TaS 3 , TaSe 4 2 I, K 0X3 MoO 3 , and NbS 3 (phase II) [54,56]. Dependences of the torsion angle on the electric field, jE , measured at different E variation rates give evidence of two contributions [56]: (1) slow Ð threshold, hysteretic (see Section 4.4, Fig.…”

Tunable harmonic vibrations of quasi one-dimensional conductors induced by sliding charge-density waves

“…4; some of the resonances could be attributed to the flexural oscillations of the micromirror. 15 Studies of the spectra S ϕ (f ) showed that harmonic torsional oscillations at f f could be excited only when f f coincides with one of the resonances [ Fig. 2(b) shows an example]: we distinguished peaks on the S ϕ (f ) curves at the resonant frequencies that could "flare up" and "dim" with dc current change.…”

“…2,3 Electric-field-induced CDW deformation is known to reveal itself in enormous nonuniform strains of the samples. 13 The kinds of nonuniform strain are likely to be various, 14,15 but the most studied one is the torsional strain (TS). 13,16,17 The threshold and hysteretic field dependences of torsional angle, δϕ(E), clearly show that TS is coupled with the CDW deformation.…”