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One of the most fascinating areas of research in mesoscopic physics is the transport properties of onedimensional
(1D) quantum wires. A quasi-1D quantum wire is realised by electrostatically squeezing a
high mobility two-dimensional-electron-gas using patterned gates fabricated on a GaAs/AlGaAs
heterostructure. In a 1D quantum wire the conductance takes quantised values, with each 1D sub-band
contributing a spin degenerate conductance of 2e2
/h and total conductance is N2e2
/h, where
N=1,2,3,4…; here the 1D electrons have freedom to change momentum in one dimension only with a
progressive filling of the sub-bands. However when electron-electron interaction is considered, a
number of 1D states are predicted, including a ferromagnetic state and various spin phases, which has
aroused a considerable interest in the research of interacting fermions in quantum wires. One of the
predictions is the observation of Wigner crystallization in low density 1D system.
In this talk, recent experimental results of a low-density quasi-1D device fabricated using GaAs/AlGaAs
heterostructure, having split-gates, top-gate combination to control the carrier density and confinement
potential would be presented. At a particular confinement configuration, and electron density, the
ground state of a 1D quantum wire splits into two rows of electrons which results in first conductance
plateau at 4e2
/h than usual 2e2
/h, which is a signature of Wigner crystallization. Non-linear transport
measurement revealed that in addition to the usual 0.25(2e2
/h) due to the lifting of momentum
degeneracy, an additional structure at 0.5(2e2
/h) is visible which indicates addition of two 0.25(2e2
/h)
structures contributed by each rows. As the confinement was weakened, the ground state which is now
a two rows system, results in anticrossing of the wavefunction due to the hybridization. In the presence
of in-plane magnetic field, the 1D subbands take a complex form due to Zeeman splitting in addition to
the Coulomb interactions. The most remarkable observation was the interaction combined with weak
confinement results in the first excited state becoming the ground state as the two rows are formed, and
the ground state moves up and crosses the higher levels. This unexpected manifestation of the electron
interaction encourages us to explore gate geometries to engineer the double rows to realize spin based
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