Complete excitation spectrum of charge-density waves: Optical experiments onK0.3MoO3<

Spectroscopic evidence for a charge-density-wave condensate in a charge-ordered manganite: Observation of a collective excitation mode inPr0.7Ca0.3Kida1, Tonouchi2 2002Phys. Rev. B835380View full textAdd to dashboardCite

“…We discuss here that the observed peak structure arises from the CDW condensate as compared to the low-energy optical properties of the well-known CDW system. The typical characteristics of the collective excitation mode observed in low-dimensional CDW materials are as follows: 16,38,39,40,41,42 (i) As mentioned earlier, the pinning frequency is in general of the order of meV. 16,38,39,40,41,42 (ii) The spectral weight of the collective excitation mode is typically 2 orders of magnitude smaller than that of the single-particle excitation.…”

“…16,38,39,40,41,42 (ii) The spectral weight of the collective excitation mode is typically 2 orders of magnitude smaller than that of the single-particle excitation. 16,38,39,40,41,42 This is due to the relatively large 2∆ ∼ 100 meV, which is in strong contrast to the small spin gap ∼ 10 meV observed in the spin-density-wave (SDW) system. In the SDW system, the spectral weight of the collective excitation mode should be comparable to that of the single-particle excitation due to the electron-electron interaction.…”

Sliding Density Wave in Sr 14 Cu 24 O 41 Ladder Compounds

“…Such was the case in CDW systems (15,16,17,18,19,20). The transfer of spectral weight to the longitudinal channel explains why the oscillator strength in the microwave region (8) is anomalously small.…”

“…This pinning shifts the oscillator strength associated with the collective modes to finite frequencies, with no contribution to the dc conductivity that shows an activated behavior and is entirely determined by quasi-particle excitations out of the condensate. The Arrhenius law for the decay constant Γ(T ) suggests a hydrodynamic origin for the Raman and lowfrequency conductivity modes, for which there is considerable precedent in studies of the dynamics of pinned CDW and SDW systems (15,16,17,18,19,20), and we compare the Sr 14 Cu 24 O 41 ladder system to well-established models of CDW dynamics (21). The pinned collective mode can be described by an oscillator making a collective contribution to the ac conductivity…”

Raman signatures of charge ordering inK0.3WO3

“…These physical properties often originate from a strong coupling between various elementary excitations in solids, such as phonons, phasons, 1 amplitudons, 2 and plasmarons. 3 Among the transition-metal oxides, tungsten bronzes have attained considerable attention due to their interesting physical properties which depend on the kind of alkali-metal atom and its composition.…”