Imaging the Zigzag Wigner Crystal in Confinement-Tunable Quantum Wires

Abstract

The existence of Wigner crystallization, one of the most significant hallmarks of strong electron correlations, has to date only been definitively observed in two-dimensional systems. In one-dimensional (1D) quantum wires Wigner crystals correspond to regularly spaced electrons; however, weakening the confinement and allowing the electrons to relax in a second dimension is predicted to lead to the formation of a new ground state constituting a zigzag chain with nontrivial spin phases and properties. Here we report the observation of such zigzag Wigner crystals by use of on-chip charge and spin detectors employing electron focusing to image the charge density distribution and probe their spin properties. This experiment demonstrates both the structural and spin phase diagrams of the 1D Wigner crystallization. The existence of zigzag spin chains and phases which can be electrically controlled in semiconductor systems may open avenues for experimental studies of Wigner crystals and their technological applications in spintronics and quantum information.

Formation of a non-magnetic, odd-denominator fractional quantized conductance in a quasi-one-dimensional electron system

“…[4][5][6][7][8][9] Of these, the 0.7(2e 2 /h) conductance anomaly, a plateau appearing just below the first conductance plateau, has been extensively investigated with considerable discussion on its origin, and this effect was linked to the intrinsic spin polarization within the 1D system by means of transverse electron focusing. [10][11][12] There have been various theoretical proposals on the possibility of nonmagnetic fractional conductance plateaux (below e 2 /h) in both 2D and 1D systems analogous to the fractional quantum Hall effect (FQHE). 13 I nt h eF Q H E ,t h ef r a c t i o n a l i z a t i o ni sp r i n c i p a l l yi nt h e form of odd-denominator fractions as a result of Coulomb interaction among electrons occupying the lowest Landau levels in the 2D system.…”

“…6,7 It has been shown that the theoretically predicted 1D Wigner crystallization can not only be observed experimentally using the conductance measurement but also be imaged as two separate charge densities using transverse electron focusing. 10 This phase is very sensitive to the confinement potential and changes in the kinetic energy of the relaxed electrons. One way to modulate the confinement, and hence the wavefunction of weakly confined electrons, is to alter the symmetry of the confinement potential by applying an offset to one of the split gates.…”

Thermoelectric Scanning-Gate Interferometry on a Quantum Point Contact

“…Alhough this localized state could result from disorder in the potential of the QPC channel, it could also correspond to a spontaneously localized charge. Indeed, several evidences for the existence of bound states in QPCs near pinch-off have been reported [39,[52][53][54][55][56]. Such bounds states have been predicted to spontaneously form in QPCs by several numerical studies [51,[57][58][59][60], as a consequence of e-e interactions.…”

Двухканальный Электронный Транспорт В Подвешенных Квантовых Точечных Контактах С Боковыми Затворами

“…Известно также, что при ослаблении ограничивающего потенциала или увеличении концентрации электронов в вигнеровском кристалле происходит фазовый переход " струна−зигзаг" [22,23], который регистрируется в измерениях кондактанса в виде удвоения ступеней квантования кондактанса. Формирование двухрядного транспорта было наглядно показано в экспериментах по поперечной магнитной электронной фокусировке [24,25]. Однако в перечисленных работах речь не идет о независимом квантовании кондактанса отдельных каналов.…”