Hall voltage drives pulsing counter-currents of the sliding charge density wave and of quantized normal carriers at self-filled Landau levelsстатья
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Дата последнего поиска статьи во внешних источниках: 15 июля 2021 г.
Аннотация:Remnant pockets of carriers left over after formation of a charge density wave (CDW) were brought, by virtue of transverse electricand magnetic fields, to a current-carrying state at quantized Landau Levels. The generated Hall voltage polarizes and puts to slidingthe flexible CDW background. The screening from the CDW allows for a so strong redistribution of normal electrons density underthe action of the Lorentz force alone, that an integer filling of the lowest Landau level might be reached at one edge at the expenseof the full depletion at another edge of the Hall bar. With the Hall field exceeding the sliding threshold, the regime of exactlycompensated collective and normal counter-currents develops in the open-circuit direction across the bar. The annihilation of thetwo currents proceeds via a regular sequence of phase slips which are the space-time vortices of the CDW phase around theenforced amplitude nodes. The resulting spontaneous generation of coherent high (~GHz) frequency signals was detected byobservations of multiple Shapiro steps. This picture results from studies of micron-sized Hall bars in crystals of NbSe3 prepared bymeans of focused ion beams. The interpretation is confirmed and illustrated by a numerical solution of the derived equations. Thedepinning pulse propagates from edges to the bulk and the sliding sets in, accompanied by the generation of periodic phase slipsnear the Hall bar edge where the CDW phase is advanced in steps of 2π at expense of the CDW amplitude passing through zero.