Many-body spin-related phenomena in ultra low-disorder quantum wires

Reilly, DJ; Facer, G. R.; Dzurak, Andrew S.; Kane, B. E.; Stiles, P.J.; Clark, R. G.; Hamilton, A. R.; O’Brien, Jeremy L; Lumpkin, N. E.; Pfeiffer, L. N.; West, K. W.

doi:10.1103/physrevb.63.121311

Cited by 144 publications

(138 citation statements)

References 23 publications

(39 reference statements)

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“…9 as a function of 1 for different values of the frequency of the lateral confining potential 0 . One sees from this figure that when the strip is in the first-polarized-subband, ␥ approximately ranges from 1.5 to 1 for all the confinements considered here, yielding for this subband a conductance that goes from G Ӎ 0.7͑2e 2 / h͒ to G Ӎ 0.5͑2e 2 / h͒ with increasing density, in agreement with the experimental data of Reilly et al 14 The discontinuity of ␥ and K when passing from one to two subbands reflects the phase transition occurring in the system. After that, the paramagnetic state has a conductance that, starting from values slightly larger than 2e 2 / h, decreases with increasing density to the measured value G Ӎ 2e 2 / h. Even though our model for an infinite quantum strip is obviously an oversimplification of the actual experimental device, it yields a qualitative agreement with measurements, especially the observed density dependence of the conductance.…”

Section: ͑38͒supporting

confidence: 81%

“…30 The evolution of the structure with density in finite-length wires is not well understood. For finitelength wires, Reilly et al 14 find additional structures in higher subbands which suggest that many-body effects are enhanced in longer 1D wires. Long quantum wires are ideal systems to address one-dimensional electron transport considering electron-electron interactions and also in the presence of impurities, which are relevant to studying the Tomonaga-Luttinger liquid.…”

Section: Introductionmentioning

confidence: 99%

“…In other words, the measured linear conductivity is the screened one, which in the random-phase approximation ͑RPA͒ used in previous calculations coincides with the free linear conductivity. Recent measurements 14 in ultra-lowdisorder quantum wires of finite length exhibit a conductance structure close to G = 0.7͑2e 2 / h͒ evolving continuosly with increasing electron density to G = 0.5͑2e 2 / h͒, the value expected for an ideal spin-split subband. The structure at G = 0.7͑2e 2 / h͒ was already observed in low-disorder quantum point contacts ͑quantum wires of zero length͒ by several authors.…”

Section: Introductionmentioning

confidence: 99%

“…Our method allows us to calculate the compressibility in all these situations-although only the cases of one and two occupied subbands are presented-and yields values for G that are in qualitative agreement with the ones found in long wires. 14 We note that a scattering matrix approach has been recently employed to calculate the conductance through a semiextended barrier or well in the wire. 34 In this case, G can be expressed in terms of the incident electron energy E in the form G = ͑2e 2 / h͚͒ n T n ͑E͒, where T n ͑E͒ is the current transmission coefficient for an electron incident in the nth subband.…”

Section: Introductionmentioning

confidence: 99%

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Ground state structure and conductivity of quantum wires of infinite length and finite width

et al. 2005

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We have studied the ground state structure of quantum strips within the local spin-density approximation, for a range of electronic densities between ϳ5 ϫ 10 4 and 2 ϫ 10 6 cm −1 and several strengths of the lateral confining potential. The results have been used to address the conductance G of quantum strips. At low density, when only one subband is occupied, the system is fully polarized and G takes a value close to 0.7͑2e 2 / h͒, decreasing with increasing electron density in agreement with experiments. At higher densities the system becomes paramagnetic and G takes a value near ͑2e 2 / h͒, showing a similar decreasing behavior with increasing electron density. In both cases, the physical parameter that determines the value of the conductance is the ratio K / K 0 of the compressibility of the system to the free one.

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Section: ͑38͒supporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ground state structure and conductivity of quantum wires of infinite length and finite width

et al. 2005

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“…The major challenge of spintronics is to avoid the use of ferromagnetic contacts or external magnetic fields and to control the creation, manipulation, and detection of spin polarized currents by purely electrical means. Some major steps towards that goal have been realized recently [3][4][5][6][7][8][9][10][11]. Spin-orbit coupling (SOC), which couples the electron's motion to its spin, has been envisioned as a possible tool for all-electric control and generation of spin-polarized currents.…”

mentioning

confidence: 99%

Tunable all electric spin polarizer

Charles

Bhandari

Wan

et al. 2013

Applied Physics Letters

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We propose a new device to create a tunable all-electric spin polarizer: a quantum point contact (QPC) with four gates --two in-plane side gates in series. The first pair of gates, near the source, is asymmetrically biased to create spin polarization in the QPC channel. The second set of gates, near the drain, is symmetrically biased and that bias is varied to maximize the amount of spin polarization in the channel. The range of common mode bias on the first set of gates over which maximum spin polarization can be achieved is much broader for the four gate structure compared with the case of a single pair of in-plane side gates.Semiconductor spintronics is one of the most promising paradigms for the development of novel devices for use in the post-CMOS era [1,2]. The major challenge of spintronics is to avoid the use of ferromagnetic contacts or external magnetic fields and to control the creation, manipulation, and detection of spin polarized currents by purely electrical means. Some major steps towards that goal have been realized recently [3][4][5][6][7][8][9][10][11]. Spin-orbit coupling (SOC), which couples the electron's motion to its spin, has been envisioned as a possible tool for all-electric control and generation of spin-polarized currents. It has been shown that SOC can be used to modulate spin polarized currents by taking advantage of symmetry-breaking factors such as interfaces, electric fields, strain, and crystalline directions [5]. Recently, we showed that lateral spin-orbit coupling (LSOC) in InAs/InAlAs and GaAs/AlGaAs quantum point contacts (QPCs) with in-plane side gates, can be used to create a strongly spin-polarized current by purely electrical means in the absence of any applied magnetic field [12][13][14][15]. Non Equilibrium Green's Function (NEGF) calculations of the conductance of QPCs show that the onset of spin polarization in devices with in-plane side gates required three ingredients: (1) a LSOC induced by a lateral confining potential in the QPC; (2) an asymmetric lateral confinement; and (3) a strong electron-electron interaction [16,17]. The NEGF approach was used to study in detail the ballistic conductance of asymmetrically biased side-gated QPCs in the presence of LSOC and strong electron-electron interactions for a wide range of QPC dimensions and gate bias voltages [17]. Various conductance anomalies were predicted below the first quantized conductance plateau (G 0 =2e 2 /h); these occur because of spontaneous spin polarization in the narrowest portion of the QPC. The number of observed conductance anomalies increases with increasing aspect ratio (length/width) of the QPC constriction. These anomalies are fingerprints of spin textures in the narrow portion of the QPC [17]. The NEGF approach was also used to show the importance of impurity and dangling bond scattering on the location of the conductance anomalies [17,18].In view of these results, it seems appropriate to find a way to control and finely tune the location of a conductance anomaly, with the goal of ach...

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Heat flow, transport and fluctuations in etched semiconductor quantum wire structures

Riha

Chiatti

Buchholz

et al. 2016

Physica Status Solidi (a)

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Low‐dimensional transport in semiconductor meso‐ and nanostructures is a topical field of fundamental research with potential applications in future quantum devices. However, thermal non‐equilibrium may destroy phase‐coherence and remains to be explored experimentally. Here, we present effects of thermal non‐equilibrium in various implementations of low‐dimensional (non‐interacting) electron systems, fabricated by etching AlGaAs/GaAs heterostructures. These include narrow quasi‐two‐dimensional (2D) channels, quasi‐one‐dimensional (1D) waveguide networks, quantum rings (QRs), and single 1D constrictions, such as quantum point contacts (QPCs). Thermal non‐equilibrium is realized by current heating. The charge carrier temperature is determined by noise thermometry. The electrical conductance and the voltage–noise are measured with respect to bath temperatures, heating currents, thermal gradients, and electric fields. We determine and discuss heat transport processes, electron‐energy loss rates, and electron–phonon interaction, and our results are consistent with the Wiedemann–Franz relation. Additionally, we show how non‐thermal current fluctuations can be used to identify electric conductance anomalies due to charge states.

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Many-body spin-related phenomena in ultra low-disorder quantum wires

Cited by 144 publications

References 23 publications

Ground state structure and conductivity of quantum wires of infinite length and finite width

Ground state structure and conductivity of quantum wires of infinite length and finite width

Tunable all electric spin polarizer

Heat flow, transport and fluctuations in etched semiconductor quantum wire structures

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