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ABSTRACT: We have investigated spin-related oscillatory magnetoresistances of the two-dimensional electron gas in the inversion layer on bulk p-Hg1−xCdxTe at low temperatures. The oscillatory magnetoresistances are found to display beating pattern at low magnetic fields and to exhibit spin-splitting structure at high magnetic fields. We attribute the beating pattern to zero-field spin splitting due to spin-orbit coupling by analyzing fast-Fourier-transform results and Hall resistance. By modulating the oscillatory magnetoresistances we investigate the influence of spin-orbit coupling, Zeeman splitting, and the second populated subband on the appearance of beating patterns and the spin-splitting structure in oscillatory magnetoresistances. The strong spin-orbit coupling and the large effective g factor are demonstrated to be the significant parameters in controlling the appearance of spin-related oscillatory magnetoresistance in the inversion layer on bulk p-Hg1−xCdxTe. A good agreement between magnetoresistance data and theory suggests a spin-orbit coupling parameter α = 2.8 × 10−11 eV•m and the effective g factor g* = −44.0. The spin-orbit coupling effect presented in the inversion layer on bulk p-Hg1−xCdxTe provides a potential candidate for spintronic devices.
Journal of Applied Physics 06/2011; 109(11):113717-113717-6. · 2.17 Impact Factor
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W. Z. Zhou,
T. Lin,
L. Y. Shang,
G. Yu,
K. H. Gao,
Y. M. Zhou,
L. M. Wei,
L. J. Cui,
Y. P. Zeng, S. L. Guo,
J. H. Chu
[show abstract]
[hide abstract]
ABSTRACT: The beating patterns in the Shubnikov-de Haas oscillatory
magnetoresistance originating from zero-field spin splitting of
two-dimensional electron gases (2DEGs) in
In0.52Al0.48As/InxGa1-xAs/In0.52Al0.48As
quantum wells with silicon δ doped on the upper barrier layer
have been investigated by means of magnetotransport measurements before
and after illumination. Contrary to the expectation, after each
illumination, the beating nodes induced by the zero-field spin-splitting
effect shift to lower and lower magnetic field due to the decrease in
the zero-field spin-splitting energy of the 2DEGs. The anomalous
phenomenon of the shift of the beating nodes and the decrease in
spin-orbit coupling constants after illumination cannot be explained by
utilizing the previous linear Rashba model. It is suggested that the
decrease in the zero-field spin-splitting energy and the spin-orbit
coupling constant arise from the nonlinear Rashba spin splitting.
Physical review. B, Condensed matter 04/2010; 81(19):195312.
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Y. M. Zhou,
G. Yu,
L. M. Wei,
K. H. Gao,
W. Z. Zhou,
T. Lin,
L. Y. Shang, S. L. Guo,
J. H. Chu,
N. Dai,
D. G. Austing
[show abstract]
[hide abstract]
ABSTRACT: We report on the strong spin-orbit (SO) interaction in a gated high-mobility In <sub>0.53</sub> Ga <sub>0.47</sub> As / InP quantum well two-dimensional electron gas. We establish that the SO interaction is dominated by the Rashba mechanism. The Rashba coupling parameters determined from analysis of both weak antilocalization and the beating pattern in the Shubnikov–de Haas oscillations are in reasonable agreement, and the small difference between them was explained by a magnetic-field-dependent effective g factor. The zero-field spin splitting shows nonmonotonic behavior with a maximum as the electron density is varied with the applied gate voltage. This is related to strong Rashba SO coupling in our sample.
Journal of Applied Physics 04/2010; · 2.17 Impact Factor
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[show abstract]
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ABSTRACT: We study the magnetotransport properties of a gated In <sub>0.53</sub> Ga <sub>0.47</sub> As / In P quantum well structure in the presence of spin splitting when only one electronic subband is occupied. We develop an analytical method to extract the quantum mobilities for the two spin subbands. Ionized impurity scattering and alloy disorder scattering are determined to be important in this system. Larger quantum mobility is found for the higher-energy spin subband. We also demonstrate that the difference between the quantum mobilities for the two spin subbands can be altered with the gate.
Journal of Applied Physics 11/2009; · 2.17 Impact Factor
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W. Z. Zhou,
T. Lin,
L. Y. Shang,
L. Sun,
K. H. Gao,
Y. M. Zhou,
G. Yu,
N. Tang,
K. Han,
B. Shen, S. L. Guo,
Y. S. Gui,
J. H. Chu
[show abstract]
[hide abstract]
ABSTRACT: The weak antilocalization (WAL) effects of the two-dimensional electron gas (2DEG) in high mobility Al <sub>x</sub> Ga <sub>1-x</sub> N / GaN heterostructure as well as beating patterns in the Shubnikov–de Haas (SdH) oscillatory magnetoresistance have been investigated by means of magnetotransport measurements before and after illumination. The zero-field spin splitting mainly arising from the Rashba spin-orbit coupling effect is studied using the weak antilocalization and beating patterns analysis, respectively. The Rashba spin-orbit coupling constant α deduced using the weak antilocalization analysis showed a good agreement with that estimated from the analysis of the beating patterns for the sample before and after illumination. For our sample, the electron motion in the high mobility system is in the ballistic regime, the experimental WAL curves were fitted by a simulated quantum conductance correction according to a model proposed by [Golub [Phys. Rev. B 71, 235310 (2005)].
Journal of Applied Physics 10/2008; · 2.17 Impact Factor
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N. Tang,
B. Shen,
K. Han,
Z. J. Yang,
K. Xu,
G. Y. Zhang,
T. Lin,
B. Zhu,
W. Z. Zhou,
L. Y. Shang, S. L. Guo,
J. H. Chu
[show abstract]
[hide abstract]
ABSTRACT: The oscillatory magnetoresistance of the two-dimensional electron gas (2DEG) in AlxGa1−xN/GaN heterostructures has been studied by means of magnetotransport measurements at low temperatures and high magnetic fields. The split peaks of the Shubnikov–de Haas oscillations are observed at high magnetic fields, which are attributed to the spin splitting of the 2DEG. It is found that the spin splitting energy becomes smaller with an increase in magnetic field, indicating that the Zeeman spin splitting is not dominant at measured magnetic field range. Within this magnetic field range, the zero-field spin splitting, as well as Zeeman spin splitting, affects the split peaks in the oscillatory magnetoresistance of the 2DEG in AlxGa1−xN/GaN heterostructures.
Journal of Applied Physics 10/2006; 100(7):073704-073704-3. · 2.17 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: 4.2 K photoluminescence (PL) and 77 K standard Hall-effect measurements were performed for In <sub>0.52</sub> Al <sub>0.48</sub> As / In <sub>x</sub> Ga <sub>1-x</sub> As metamorphic high-electron-mobility-transistor (HEMT) structures grown on GaAs substrates with different indium contents in the In <sub>x</sub> Ga <sub>1-x</sub> As well or different Si delta-doping concentrations. It was found that electron concentrations increased with increasing PL intensity ratio of the “forbidden” transition (the second electron subband to the first heavy-hole subband) to the sum of the “allowed” transition (the first electron subband to the first heavy-hole subband) and the forbidden transition. And electron mobilities decreased with increasing product of the average full width at half maximum of allowed and forbidden transitions and the electron effective mass in the In <sub>x</sub> Ga <sub>1-x</sub> As quantum well. These results show that PL measurements are a good supplemental tool to Hall-effect measurements in optimization of the HEMT layer structure.
Journal of Applied Physics 09/2006; · 2.17 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Shubnikov–de Haas measurements were carried out for In0.52Al0.48As/InxGa1−xAs metamorphic high-electron-mobility-transistor structures grown on GaAs substrates with different indium contents and/or different Si δ-doping concentrations. Zero-field (B→0) spin splitting was found in samples with stronger conduction band bending in the InGaAs well. It was shown that the dominant spin splitting mechanism is attributed to the contribution by the Rashba term. We found that zero-field spin splitting not only occurs in the ground electron subband, but also in the first excited electron subband for a sample with Si δ-doping concentration of 6×1012 cm−2. We propose that this In0.52Al0.48As/InxGa1−xAs metamorphic high-electron-mobility-transistor structure grown on GaAs may be a promising candidate spin-polarized field-effect transistors. © 2002 American Institute of Physics.
Applied Physics Letters 04/2002; 80(17):3132-3134. · 3.84 Impact Factor
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[show abstract]
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ABSTRACT: A Shubnikov–de Haas (SdH) oscillation measurement was performed on highly doped InAlAs/InGaAs metamorphic high-electron-mobility transistors on GaAs substrates at a temperature of 1.4 K. By analyzing the experimental data using fast Fourier transform, the electron densities and mobilities of more than one subband are obtained, and an obvious double-peak structure appears at high magnetic field in the Fourier spectrum. In comparing the results of SdH measurements, Hall measurements, and theoretical calculation, we found that this double-peak structure arises from spin splitting of the first-excited subband (i = 1). Very close mobilities of 5859 and 5827 cm2/V s are deduced from this double-peak structure. The sum of the carrier concentration of all the subbands in the quantum well is only 3.95×1012 cm−2 due to incomplete transfer of the electrons from the Si δ-doped layer to the well. © 2001 American Institute of Physics.
Applied Physics Letters 09/2001; 79(12):1909-1911. · 3.84 Impact Factor
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C. P. Jiang,
Z. M. Huang,
Z. F. Li,
J. Yu, S. L. Guo,
W. Lu,
J. H. Chu,
L. J. Cui,
Y. P. Zeng,
Z. P. Zhu,
B. Q. Wang
[show abstract]
[hide abstract]
ABSTRACT: InAlAs/InGaAs metamorphic high-electron-mobility transistor structures with different spacer layers on GaAs substrates are characterized by Raman measurements. The influence of In0.52Al0.48As spacer thickness on longitudinal optic phonon–plasmon coupling is investigated. It is found that the intensity of GaAs-like longitudinal optic phonon, which couples with collective intersubband transitions of two-dimensional electron gas, is strongly affected by the different subband energy spacings, subband electron concentrations, and wave function distributions, which are determined by different spacer thicknesses. © 2001 American Institute of Physics.
Applied Physics Letters 08/2001; 79(9):1375-1377. · 3.84 Impact Factor
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W Z Zhou,
T Lin,
L Y Shang,
L Sun,
K H Gao,
Y M Zhou,
G Yu,
N Tang,
K Han,
B Shen, S L Guo,
Y S Gui,
J H Chu
[show abstract]
[hide abstract]
ABSTRACT: The weak antilocalization effects of the two-dimensional electron gas in a high mobility Al x Ga 1−x N / GaN heterostructure have been investigated by means of magnetotransport measurements before and after illumination. The zero-field spin splitting mainly arising from the Rashba spin-orbit coupling effect as a function of electron concentration as well as a function of temperature is studied using the weak antilocalization analysis. The Rashba spin-orbit coupling constant deduced using the weak antilocalization analysis shows a rapid decrease with the increase of the measured electron concentration. © 2008 American Institute of Physics. Two-dimensional electron gases 2DEGs in Al x Ga 1−x N / GaN heterostructure are very promising candi-dates for future spintronic applications based on the facts that 1,2 GaN-based diluted magnetic semiconductors are pro-spective materials for spin injection or spin analyzer because they show Curie temperatures above room temperature and are expected to be a good match to Al x Ga 1−x N / GaN hetero-structures. Besides, 2DEGs in Al x Ga 1−x N / GaN heterostruc-tures are potential candidates for gate-controlled spin preces-sion utilizing the Rashba effect 3 induced by structural inversion asymmetry SIA of quantum well. In wurtzite Al x Ga 1−x N / GaN heterostructures, the zero-field spin splitting can originate from the Rashba effect and the effect induced by the lack of inversion symmetry of the wurtzite-type lattice, i.e., the bulk inversion asymmetry BIA. The electric field originating from the BIA in wurtzite Al x Ga 1−x N / GaN heterostructures is oriented along the 0001 direction and thus parallel to the macroscopic electric field in the SIA quantum well. 1,2 And both the Rashba and BIA terms are linear scaling of the Fermi wave vector k f . 4 The Rashba spin-orbit SO coupling is of particular interest due to its potential applications in spin-field-effect transistor in the ballistic regime, as it can be controlled by an applied gate voltage. 5 The zero-field spin splitting in Al x Ga 1−x N / GaN hetero-structures has attracted considerable and continuously grow-ing interest for the application in the spintronic devices. Recent experiments based on Shubnikov–de Haas SdH, weak antilocalization WAL, and circular photogalvanic measurements have given conflicting results such as the original mechanisms for the zero-field spin splitting of the 2DEG, as well as the magnitude of SO interaction in wurtzite Al x Ga 1−x N / GaN heterostructures. 1,2,4,6–11 Thillosen et al.
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W.Z. Zhou,
Z.M. Huang,
Z.J. Qiu,
T. Lin,
L.Y. Shang,
D.L. Li,
H.L. Gao,
L.J. Cui,
Y.P. Zeng, S.L. Guo,
Y.S. Gui,
N. Dai,
J.H. Chu
[show abstract]
[hide abstract]
ABSTRACT: Magneto-transport measurements have been carried out on double/single-barrier-doped In0.52Al0.48As/ In0.53Ga0.47As/ In0.52Al0.48As quantum well samples from 1.5 to 60 K in an applied magnetic field up to 13 T. Beating Shubnikov–de Haas oscillation is observed for the symmetrically double-barrier-doped sample and demonstrated due to a symmetric state and an antisymmetric state confined in two coupled self-consistent potential wells in the single quantum well. The energy separation between the symmetric and the antisymmetric states for the double-barrier-doped sample is extracted from experimental data, which is consistent with calculation. For the single-barrier-doped sample, only beating related to magneto-intersubband scattering shows up. The pesudospin property of the symmetrically double-barrier-doped single quantum well shows that it is a good candidate for fabricating quantum transistors.
Solid State Communications 142(7):393-397. · 1.65 Impact Factor
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W. Z. Zhou,
T. Lin,
L. Y. Shang,
G. Yu,
K. H. Gao,
Y. M. Zhou,
L. M. Wei,
L. J. Cui,
Y. P. Zeng, S. L. Guo,
J. H. Chu
[show abstract]
[hide abstract]
ABSTRACT: The beating patterns in the Shubnikov-de Haas oscillatory magnetoresistance originating from zero-field spin splitting of two-dimensional electron gases (2DEGs) in In0.52Al0.48As/InxGa1−xAs/In0.52Al0.48As quantum wells with silicon δ doped on the upper barrier layer have been investigated by means of magnetotransport measurements before and after illumination. Contrary to the expectation, after each illumination, the beating nodes induced by the zero-field spin-splitting effect shift to lower and lower magnetic field due to the decrease in the zero-field spin-splitting energy of the 2DEGs. The anomalous phenomenon of the shift of the beating nodes and the decrease in spin-orbit coupling constants after illumination cannot be explained by utilizing the previous linear Rashba model. It is suggested that the decrease in the zero-field spin-splitting energy and the spin-orbit coupling constant arise from the nonlinear Rashba spin splitting.
Phys. Rev. B. 81(19).
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W.Z. Zhou,
T. Lin,
L.Y. Shang,
G. Yu,
Z.M. Huang, S.L. Guo,
Y.S. Gui,
N. Dai,
J.H. Chu,
L.J. Cui,
D.L. Li,
H.L. Gao,
Y.P. Zeng
[show abstract]
[hide abstract]
ABSTRACT: We have observed the weak antilocalization (WAL) and beating SdH oscillation through magnetotransport measurements performed on a heavily δ-doped In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As single quantum well in an applied magnetic field up to 13 T and a temperature at 1.5 K. Both effects are caused by the strong Rashba spin–orbit (SO) coupling due to high structure inversion asymmetry (SIA). The Rashba SO coupling constant α and zerofield spin splitting are estimated and the obtained values are consistent from different analysis for this sample.
Solid State Communications.
