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Wróbel, J.; Dietl, T.; Regiński, K.; Bugajski, M.

doi:10.1103/physrevb.58.16252

Cited by 6 publications

(14 citation statements)

References 62 publications

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“…2 of Ref. 38 showing a nonmonotonic dependence of the conductance of a quantum wire as a function of magnetic field, are consistent with the predicted behavior of the total current. Note that this feature in the conductance also survives within the DFT approach (see below, Fig.…”

Section: A Hartree Approximationsupporting

confidence: 87%

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Spin polarization of edge states and the magnetosubband structure in quantum wires

2006

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We provide a quantitative description of the structure of edge states in split-gate quantum wires in the integer quantum Hall regime. We develop an effective numerical approach based on the Green's function technique for the self-consistent solution of Schrödinger equation where electron-and spin interactions are included within the density functional theory in the local spin density approximation. The major advantage of this technique is that it can be directly incorporated into magnetotransport calculations, because it provides the self-consistent eigenstates and wave vectors at a given energy, not at a given wavevector (as conventional methods do). We use the developed method to calculate the subband structure and propagating states in the quantum wires in perpendicular magnetic field starting with a geometrical layout of the wire. We discuss how the spin-resolved subband structure, the current densities, the confining potentials, as well as the spin polarization of the electron and current densities evolve when an applied magnetic field varies. We demonstrate that the exchange and correlation interactions dramatically affect the magnetosubbands in quantum wires bringing qualitatively new features in comparison to a widely used model of spinless electrons in Hartree approximation. I. INRODUCTIONTransport properties of quantum dots, antidots and related structures are affected by the nature of currentcarrying states in the leads connecting these structures to electron reservoirs. In sufficiently high magnetic fields the current-carrying states are the edge states propagating in a close vicinity to the sample boundaries 1 . A detailed information on the structure of the edge states represent a key to the understanding of various features of the magnetotransport in the quantum Hall regime.A quantitative description of the edge states for the case of the gate-induced confinement of the highmobility two-dimensional electron gas (2DEG) was given by Chklovskii et al.2 , who provided an analytical solution for the positions and widths of the compressible and incompressible strips arising in the 2DEG due to the electrostatic screening. In the compressible regions, the Landau bands are pinned at the Fermi energy E F . This leads to a metallic behavior when the electron density is redistributed (compressed) to keep the electrostatic potential constant. In the incompressible regions, where the Fermi energy lies in the Landau gaps, all the levels below E F are completely filled and hence the electron density is constant (which is consistent with the behavior of the incompressible liquid).A number of studies addressing the problem of electron-electron interaction in quantum wires beyond the electrostatic treatment of the edge states of Chklovskii et al.2 have been reported during the recent decade 3,4,5,6,7,8,9,10,11,12,13,14 . The many-body aspects of the problem have been included within ThomasFermi 3 , Hartree-Fock 4,5,6 , screened Hartree-Fock 7 , and the density functional theory 8,9 . The full quantummechanical calc...

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Section: A Hartree Approximationsupporting

confidence: 87%

“…In a typical experimental condition, a long quantum wire is connected to a much wider region of 2DEG 38 . The edge states in the region of 2DEG are coupled only to the edge states in the wire.…”

Section: A Hartree Approximationmentioning

confidence: 99%

Spin polarization of edge states and the magnetosubband structure in quantum wires

2006

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“…The coexistence of these two effects was already observed experimentally in quasi-ballistic quantum wires [18,19,20] and is also present for the device studied here. Figure 2 shows conductance measured at various temperature in the He-4 cryostat and the dilution refrigerator.…”

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confidence: 50%

0.7 anomaly and magnetotransport of disordered quantum wires

et al. 2008

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The unexpected "0.7" plateau of conductance quantisation is usually observed for ballistic onedimensional devices. In this work we study a quasi-ballistic quantum wire, for which the disorder induced backscattering reduces the conductance quantisation steps. We find that the transmission probability resonances coexist with the anomalous plateau. The studies of these resonances as a function of the in-plane magnetic field and electron density point to the presence of spin polarisation at low carrier concentrations and constitute a method for the determination of the effective g-factor suitable for disordered quantum wires.PACS numbers: 73.63. Nm, 73.23.Ad, 72.25.Dc It is expected that quantum point contacts (QPC) and quantum wires (QW) will act as active components of future nano-electronic devices and circuits. Therefore, the renewed interest in transport and spin properties of one-dimensional (1D) systems recently takes place in the mesoscopic physics community. In those studies, special attention is directed towards the long standing problem of quantum transport -the so called "0.7 anomaly" [1] most often, but not exclusively, observed for devices fabricated on modulation doped GaAs/AlGaAs heterostructures. Usually, anomalous behavior is observed in transport data as a "kink" on the conductance G vs. the device width curve, occurring for the low carrier densities, when G ∼ 0.7 × 2e 2 /h, here −e is the electron charge and h is the Planck constant. The origin of this effect is currently under active debate since this anomaly seems to be an universal, but still unexplained feature of one-dimensional mesoscopic transport. Experimentally, the magnetic field dependence of the additional plateau is common for all studied systems -by applying a parallel in-plane field the 0.7 feature evolves gradually towards 0.5 × 2e 2 /h conductance step, when only one spinpolarised level is occupied [1,2,3,4,5,6]. Therefore, it has been suggested that such an anomalous plateau is due to spontaneous spin polarisation of one-dimensional electron liquid, caused by exchange interactions among carriers in the constricted geometry of the device [2,7]. If it is so, the 1D systems may be used as an efficient spin filter with possible practical applications. This point of * Also at Instytut Fizyki Teoretycznej, Uniwersytet Warszawski, Hoża 69, PL 00-681 Warszawa, Poland; ERATO Semiconductor Spintronics Project, Japan Science Technology Agency, 1-18 Kitamemachi, Aoba-ku Sendai, 980-0023, Japan † Also at ERATO Semiconductor Spintronics Project, Japan Science and Technology Agency, 1-18 Kitamemachi, Aoba-ku Sendai, 980-0023, Japan view is supported by magnetic focusing data obtained for the p-type device, which reveal the static spin polarisation of holes transmitted through the constriction [8].Furthermore, recent shot-noise measurements carried out for n-type QPC [9] show that distinct transport channels exist at G < 2e 2 /h = G 0 , presumably related to spin, exhibiting quite different transmission probabilities.Many experiments, howeve...

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“…The experiments, however, show that the extent of these transition regions can be comparable to the width of the plateaus. 3,4,6,7 This indicates that an accurate description of the magnetoconductance in the IQH regime-even without accounting for spin effectsrequires approaches that go beyond a simple one-electron picture of noninteracting electrons. A quantitative electrostatic theory of interacting electrons in quantum wires was proposed by Chklovskii et al 8 They demonstrated that in a strong magnetic field, alternating strips of compressible and incompressible liquids are formed in the center of the wire.…”

Section: Introductionmentioning

confidence: 99%

Magnetoconductance of interacting electrons in quantum wires: Spin density functional theory study

Ihnatsenka

Zozoulenko

2008

Phys. Rev. B

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We present a systematic quantitative description of the magnetoconductance of split-gate quantum wires focusing on formation and evolution of the odd ͑spin-resolved͒ conductance plateaus. We start from the case of spinless electrons where the calculated magnetoconductance in the Hartree approximation shows the plateaus quantized in units of 2e 2 / h separated by transition regions, whose width grows as the magnetic field is increased. We show that the transition regions are related to the formation of the compressible strips in the middle of the wire occupied by electrons belonging to the highest ͑spin-degenerate͒ subband. Accounting for the exchange and correlation interactions within the spin density functional theory ͑DFT͒ leads to the lifting of the spin degeneracy and formation of the spin-resolved plateaus at odd values of e 2 / h. The most striking feature of the magnetoconductance is that the width of the odd conductance steps in the spin DFT calculations is equal to the width of the transition intervals between the conductance steps in the Hartree calculations. A detailed analysis of the evolution of the Hartree and the spin DFT subband structure provides an explanation of this finding. Our calculations also reveal the effect of the collapse of the odd conductance plateaus for lower fields. We attribute this effect to the reduced screening efficiency in the confined ͑wire͒ geometry when the width of the compressible strip in the center becomes much smaller than the extent of the wave function. A detailed comparison to the experimental data demonstrates that the spin DFT calculations reproduce not only qualitatively but also quantitatively all the features observed in the experiment. This includes the dependence of the width of the odd and even plateaus on the magnetic field as well as the estimation of the subband index corresponding to the last resolved odd plateau in the magnetoconductance.

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Transport and tunneling within a compressible electron liquid in wires and rings ofGaAs/Alx

Cited by 6 publications

References 62 publications

Spin polarization of edge states and the magnetosubband structure in quantum wires

Spin polarization of edge states and the magnetosubband structure in quantum wires

0.7 anomaly and magnetotransport of disordered quantum wires

Magnetoconductance of interacting electrons in quantum wires: Spin density functional theory study

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