Coulomb Drag Between Parallel Ballistic Quantum Wires

TL;DR

This paper theoretically investigates Coulomb drag in parallel ballistic quantum wires under a magnetic field, revealing peaks in transresistance related to Fermi level crossings and subband transitions, with nonmonotonic B dependence.

Contribution

It introduces a detailed theoretical analysis of Coulomb drag in ballistic quantum wires with magnetic field effects, highlighting new peak behaviors and nonmonotonic magnetic field dependence.

Findings

Transresistance R_D exhibits peaks at Fermi level crossings and subband transition points.

R_D decreases with magnetic field B due to suppression of backscattering.

R_D sharply increases near subband bottoms because of enhanced Coulomb interactions.

Abstract

The Coulomb drag between parallel, {\it ballistic} quantum wires is studied theoretically in the presence of a perpendicular magnetic field B. The transresistance R_D shows peaks as a function of the Fermi level and splitting energy between the 1D subbands of the wires. The sharpest peaks appear when the Fermi level crosses the subband extrema so that the Fermi momenta are small. Two other kinds of peaks appear when either {\it intra}- or {\it inter}-subband transitions of electrons have maximum probability; the {\it intra}-subband transitions correspond to a small splitting energy. R_D depends on the field B in a nonmonotonic fashion: it decreases with B, as a result of the suppression of backscattering, and increases sharply when the Fermi level approaches the subband bottoms and the suppression is outbalanced by the increase of the Coulomb matrix elements and of the density of states.