Electronic transport through a nuclear-spin-polarization-induced quantum wire

Pershin, Yuriy V.; Shevchenko, S. N.; Vagner, I. D.; Wyder, P.

doi:10.1103/physrevb.66.035303

Cited by 19 publications

(22 citation statements)

References 15 publications

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“…Recently, there have been numerous studies of the properties of quasi-one-dimensional systems. [1][2][3][4][5][6][7][8] The motivation behind this interest has been the observation of conductance quantization. Most quasi-one-dimensional systems, or quantum wires, are created by a split gate technique in a twodimensional electron gas ͑2DEG͒.…”

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confidence: 99%

“…5 Within this approximation, the effective magnetic field due to the polarized nuclear spins can be considered quasistatic and relations presented above can be used to describe the conductance.…”

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confidence: 99%

“…18 The characteristic energy scale of the interaction between conduction electrons and polarized nuclear spins makes it possible to confine the electrons into low-dimensional electron structures using modulation of the nuclear spin polarization. 5,[19][20][21][22] We assume that B ជ N is parallel to the external magnetic field B ជ ext . 16 Recent studies of 2DEG-based systems [23][24][25] have been focused on including the effects of the spin-orbit interaction on the conductance with perfect channel transmission T(E) ϭ1.…”

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Effect of spin-orbit interaction and in-plane magnetic field on the conductance of a quasi-one-dimensional system

2004

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We study the effect of spin-orbit interaction and in-plane effective magnetic field on the conductance of a quasi-one-dimensional ballistic electron system. The effective magnetic field includes the externally applied field, as well as the field due to polarized nuclear spins. The interplay of the spin-orbit interaction with effective magnetic field significantly modifies the band structure, producing additional sub-band extrema and energy gaps, introducing the dependence of the sub-band energies on the field direction. We generalize the Landauer formula at finite temperatures to incorporate these special features of the dispersion relation. The obtained formula describes the conductance of a ballistic conductor with an arbitrary dispersion relation.Recently, there have been numerous studies, both theoretical and experimental, of the properties of quasi-one-dimensional systems [1][2][3][4][5][6][7][8]. The motivation behind this interest has been the observation of conductance quantization. Most quasi-one-dimensional systems, or Quantum Wires (QW), are created by a split gate technique in a two-dimensional electron gas (2DEG) [6,7]. When a negative potential is applied to the gates, the electrons are depleted underneath. Thus, a one-dimensional channel or constriction is created between two reservoirs, in this case the 2DEG. For ballistic transport to occur [1], this constriction should be less than the electron mean free path, and have a width of the order of de Broglie wavelength [6][7][8]. When these conditions are satisfied, the electrons will move ballistically in the lateral direction and are confined transversely. The transverse confinement creates a discrete set of modes in the channel.The explanation for conductance quantization is found by using a non-interacting electron model.With a small bias applied across the channel, the electrons move from one reservoir to the other. Due to the transverse confinement in channel, the electrons are distributed, according to the Fermi-Dirac distribution, among various sub-bands in the channel. The calculation of the conductance has been summarized in the Landauer-Büttiker formalism [6][7][8]. Each one of the sub-bands contributes to the conductance.

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Effect of spin-orbit interaction and in-plane magnetic field on the conductance of a quasi-one-dimensional system

2004

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“…In our calculations we use some ideas from Ref. 16, where a nuclear-spinpolarization-induced quantum wire was proposed and investigated.…”

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Electronic structure of nuclear-spin-polarization-induced quantum dots

Pershin¹

2004

Phys. Rev. B

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We study a system in which electrons in a two-dimensional electron gas are confined by a nonhomogeneous nuclear-spin polarization. The system consists of a heterostructure that has nonzero nuclei spins. We show that in this system electrons can be confined into a dot region through a local nuclear-spin polarization. The nuclear-spin-polarization-induced quantum dot has interesting properties indicating that electron energy levels are time dependent because of the nuclear-spin relaxation and diffusion processes. Electron confining potential is a solution of diffusion equation with relaxation. Experimental investigations of the time dependence of electron energy levels will result in more information about nuclear-spin interactions in solids.

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“…This offers a new detector design, with the operation based on a new effect arising as a consequence of the combined influence of the spin-orbit interaction and nuclear spin polarization on the electron subsystem. Recent progress in investigations of QWs [17,18,19,20,21,22,23,24,25,26,27,28] makes them a promising nanoscale device component.We consider transport through a QW in the presence of an external in-plane magnetic field, Rashba spin-orbit coupling [29] and a nonequilibrium nuclear spin polarization. We assume that the external magnetic field is directed along a wire.…”

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Polarization of Nuclear Spins from the Conductance of Quantum Wire

2004

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We devise an approach to measure the polarization of nuclear spins via conductance measurements. Specifically, we study the combined effect of external magnetic field, nuclear spin polarization, and Rashba spin-orbit interaction on the conductance of a quantum wire. Nonequilibrium nuclear spin polarization affects the electron energy spectrum making it time-dependent. Changes in the extremal points of the spectrum result in time-dependence of the conductance. The conductance oscillation pattern can be used to obtain information about the amplitude of the nuclear spin polarization and extract the characteristic time scales of the nuclear spin subsystem.PACS numbers: 72.25. Dc, The promise of spintronics and quantum computing has motivated recent theoretical and experimental investigations of spin-related effects in semiconductor heterostructures [1,2,3,4,5,6,7,8,9,10]. Nuclear and electron spins have been considered as candidates for qubit implementations in solid state systems [1,2,3,4,5,6]. The final stage of a quantum computation process involves readout of quantum information. In the case of a spin qubit one would have to measure the state of a single spin. Yet, in spite of recent efforts in this field, a single nuclear spin measurement is still a great challenge.There are several proposals for single-and few-spin measurement. For example, a change of the oscillation frequency of a micro-mechanical resonator (cantilever) [11] is used. Another possibility to obtain information about a qubit state lies in the measurement [12] of current or its noise spectrum in a mesoscopic system (e.g., quantum wire, quantum dot, or single electron transistor) coupled to a qubit [13,14,15]. Significant progress in spin measurements has been made using magnetic resonance force microscopy [16], which presently allows one to probe the state of 100 fully polarized electron spins. Recently, an experimental architecture to manipulate the magnetization of nuclear spin domains was proposed [5,6].The present work demonstrates that a relatively small ensemble of nuclear spins can significantly influence transport through a quantum wire (QW). This offers a new detector design, with the operation based on a new effect arising as a consequence of the combined influence of the spin-orbit interaction and nuclear spin polarization on the electron subsystem. Recent progress in investigations of QWs [17,18,19,20,21,22,23,24,25,26,27,28] makes them a promising nanoscale device component.We consider transport through a QW in the presence of an external in-plane magnetic field, Rashba spin-orbit coupling [29] and a nonequilibrium nuclear spin polarization. We assume that the external magnetic field is directed along a wire. If the nuclear spin polarization has a non-zero component perpendicular to the external field at the initial moment of time (i.e. the two vectors are not aligned), then we will demonstrate that the conductance of the wire exhibits damped oscillations. These oscillations are a direct consequence of the interplay between the evol...

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Electronic transport through a nuclear-spin-polarization-induced quantum wire

Cited by 19 publications

References 15 publications

Effect of spin-orbit interaction and in-plane magnetic field on the conductance of a quasi-one-dimensional system

Effect of spin-orbit interaction and in-plane magnetic field on the conductance of a quasi-one-dimensional system

Electronic structure of nuclear-spin-polarization-induced quantum dots

Polarization of Nuclear Spins from the Conductance of Quantum Wire

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