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R Currat

Publications and source records attributed to R Currat.

18 recordsLinked to original sources
PubMed2004

Sliding-induced decoupling and charge transfer between the coexisting Q1 and Q2 charge density waves in NbSe3.

Using high-resolution x-ray scattering in the presence of an applied current, we report evidence for a dynamical decoupling between the two NbSe3 charge-density waves (CDWs), Q1 (T(C1)=145 K) and Q2 (T(C2)=59 K), coexisting below T(C2). Simultaneous and oppositely directed shifts of the relevant CDW superlattice spots develop above a threshold current which we identify as the depinning threshold I(C1) for the more strongly pinned upper CDW Q1 (I(C1) approximately 10I(C2)). In contrast with shifts induced by current conversion processes, the present effect is not current polarized and is not limited to the current-contact regions. We propose a model which explains this instability through a sliding-induced charge transfer between the two electronic reservoirs corresponding to the Q1 and Q2 CDWs.

Journal Article↗
PubMed2002

Motional ordering of a charge-density wave in the sliding state.

We have used high-resolution x-ray scattering, in the presence of an applied direct current, for studying the correlation lengths in the sliding charge-density wave (CDW) state. Transport properties were simultaneously measured in situ during the experiment. We find that, while the transverse correlation is reduced when the CDW moves, the CDW becomes more ordered in the direction of motion. This is the first report of a motional ordering process in a periodic system other than a vortex lattice.

Journal Article↗
PubMed2001

Structural evidence for Ta-tetramerization displacements in the charge-density-wave compound (TaSe4)2I from x-ray anomalous diffraction.

We use the anomalous x-ray diffraction technique to investigate the nature of the tantalum displacement pattern in the modulated phase of the charge-density-wave compound (TaSe4)2I. In addition to the known acousticlike modulation, we find the first direct evidence for the condensation of opticlike Ta displacements along the metallic chains corresponding to an LLSS pattern of long and short in-chain Ta-Ta distances (Ta-tetramerization modes). This result confirms a previous model in which the interaction of the electronically coupled optic modes with long-wavelength acoustic shear modes leads to the condensation of a modulation of mixed character.

Journal Article↗