72 research outputs found
Dynamical transport properties of NbSe with simultaneous sliding of both charge density waves
Measurements of the nonlinear conductivity in NbSe when the high-T and
the low-T charge-density waves (CDWs) are simultaneously sliding have been
performed. It is shown that the threshold electric field, , for
depinning the high-T CDW increases 4 - 5 times at the temperature at which the
low-T CDW is formed, indicating the strong pinning effect resulting from the
interaction between both CDWs. Under application of a radio-frequency (rf)
field, Shapiro steps are never observed simultaneously for both CDWs. At the
electric field less then one for high-T CDW sliding only Sapiro steps for low-T
CDW were observed, and at higher field only Shapiro steps for high-T CDW exist.Comment: 5 pages, 6 figures, accepted in PR
Toward equilibrium ground state of charge density waves in rare-earth tritellurides
We show that the charge density wave (CDW) ground state below the Peierls
transition temperature, , of rare-earth tritellurides is not at its
equilibrium value, but depends on the time where the system was kept at a fixed
temperature below . This ergodicity breaking is revealed by the
increase of the threshold electric field for CDW sliding which depends
exponentially on time. We tentatively explain this behavior by the
reorganization of the oligomeric (Te) sequence forming the CDW
modulation.Comment: 10 pages, 5 figures, accepted in PR
Anomalous asymmetry of magnetoresistance in NbSe single crystals
A pronounced asymmetry of magnetoresistance with respect to the magnetic
field direction is observed for NbSe crystals placed in a magnetic field
perpendicular to their conducting planes. It is shown that the effect persists
in a wide temperature range and manifests itself starting from a certain
magnetic induction value , which at K corresponds to the
transition to the quantum limit, i.to the state where the Landay level
splitting exceeds the temperature.Comment: 4 pages, 6 figures, to be appeared in JETP Let
Charge density wave sliding driven by an interplay of conventional and Hall voltages in NbSe microbridges
Collective charge-density wave (CDW) transport was measured under a high
magnetic field in NbSe microbridges which have been cut transversely and at
an angle to the chains' direction. We give evidences that the CDW sliding is
driven by the Hall voltage generated by the inter-chain current of normal
carriers. We have discovered a re-entrance effect of the Hall-driven sliding
above a crossover temperature at which the Hall constant has been known to
change sign. For the narrow channel, cut at 45 relative to the chain
axis, we observed an evolution from the Hall-driven sliding at low
temperatures, to the conventional sliding at higher temperatures, which
corroborates with falling of the Hall constant. In this course, the nonlinear
contribution to the conductivity coming from the collective sliding changes
sign. The quantization of Shapiro-steps, generated presumably by a coherent
sequence of phase slips, indicates that their governing changes from the
applied voltage to the current.Comment: 6 pages, 5 figures, accepted in PR
Character of electron reflection at a normal metal-Peierls semiconductor boundary
The reflection of electrons incident from a normal metal on the boundary of
the metal with a quasi-one-dimensional conductor containing a charge-density
wave (CDW) is investigated theoretically. It is shown that the reflection is
not of an Andreev character, as it was suggested earlier, but rather of a Bragg
character. This is due to the fact that the CDW is actually an electronic
crystal, and its wave vector is a reciprocal lattice vector of the electronic
crystal. The ratio of the intensities of the standard and Bragg reflection
depends on the phase of the CDW.Comment: 9 pages, no figures, revte
Sliding charge-density-wave in two-dimensional rare-earth tellurides
Nonlinear transport properties are reported in the layered DyTe compound
at temperature below the charge-density-wave (CDW) transition, K.
Conductivity is increasing sharply above the threshold electric field. Under
application of a rf field Shapiro steps are clearly observed. These features
demonstrate for the first time CDW sliding in two-dimensional compounds.Comment: 4 pages, 4 figure
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