Effect of well thickness on the Rashba spin splitting and intersubband spin–orbit coupling in AlGaN/GaN/AlGaN quantum wells with two subbands

Li, M.; Lv, Yuanjie; Yang, Baiyuan; Zhao, Zheng‐Yin; Sun, Guan; Miao, Dongpeng; Zhao, Chunzhang

doi:10.1016/j.ssc.2011.09.013

Cited by 13 publications

(9 citation statements)

References 21 publications

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“…Figure 3(b) further shows the several terms of α H [see Eqs. ( 44)- (47)]. For the GaN and Al 0.3 Ga 0.7 N layers, we obtain α bulk (GaN) = 1.938 meV•Å and α bulk (AlGaN) = 1.570 meV•Å.…”

Section: One Occupied Subbandmentioning

confidence: 79%

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Spin-orbit coupling in wurtzite heterostructures

Penteado

Candido

et al. 2020

Phys. Rev. B

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Effective spin-orbit (SO) Hamiltonians for conduction electrons in wurtzite heterostructures are lacking in the literature, in contrast to zincblende structures. Here we address this issue by deriving such an effective Hamiltonian valid for quantum wells, wires, and dots with arbitrary confining potentials and external magnetic fields. We start from an 8×8 Kane model accounting for the s-p z orbital mixing important to wurtzite structures, but absent in zincblende, and apply both quasi-degenerate perturbation theory (Löwdin partitioning) and the folding down approach to derive an effective 2×2 electron Hamiltonian. Focusing on wurtzite quantum wells, we later on also perform a self-consistent Poisson-Schrödinger calculation in the Hartree approximation to determine the relevant SO couplings. We obtain the usual k-linear Rashba term arising from the structural inversion asymmetry of the wells and, differently from zincblende structures, a bulk Rashba-type term induced by the inversion asymmetry of the wurtzite lattice. Our results show this latter term to be the main contribution to the Rashba coupling in wurtzite wells. We also find linear-and cubic-in-momentum Dresselhaus contributions. Both the bulk Rashba-type term and the Dresselhaus terms originate exclusively from the admixture of s-and p z -like states in wurtzites structures. Interestingly, in these systems the linear Rashba and the Dresselhaus terms have the same symmetry and can in principle cancel each other out completely, thus making the spin a conserved quantity. We determine the intrasubband (intersubband) Rashba α ν (η) and linear Dresselhaus β ν (Γ) SO strengths of GaN/AlGaN single and double wells with one and two occupied subbands (ν = 1, 2). For the GaN/Al 0.3 Ga 0.7 N single well with one occupied subband, we obtain the total spin splitting coefficient α eff 1 = α 1 + β 1 ∼ 7.16 meV·Å, in agreement with weak antilocalization measurements. In the case of two occupied subbands, we observe that the intersubband Rashba η is much weaker than the intrasubband coupling α ν . For double wells even in the presence of strong built-in electric fields (spontaneous and piezoelectric, crucial in GaN/AlGaN wells), we find a seemingly symmetric potential configuration at which both the Rashba η and Dresselhaus Γ intersubband couplings exhibit their highest strengths. On the other hand, we observe that the intrasubband Dresselhaus coefficients β 1 and β 2 interchange their values as the gate voltage V g varies across zero; a similar behavior, though less pronounced, is seen for the Rashba couplings α 1 and α 2 . We believe our general effective Hamiltonian for electrons in wurtzite heterostructures put forward here, should stimulate additional theoretical works on wurtzite quantum wells, wires, and dots with variously defined geometries and external magnetic fields.

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Section: One Occupied Subbandmentioning

confidence: 79%

“…(24)] from the 8×8 Kane model for wurtzite heterostructures. As opposed to what has been reported in the literature [36,46,47], we arrive at a genuine Schrödinger-type equation, i.e., an energyindependent effective Hamiltonian, since we account for the renormalization of the conduction band spinor component (Appendix C).…”

Section: Introductionmentioning

confidence: 99%

Spin-orbit coupling in wurtzite heterostructures

Penteado

Candido

et al. 2020

Phys. Rev. B

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“…The research on the relationship between the strain and spin effect in magnetic‐electric thin films has been widely studied worldwide; the strain in the thin films could influence the magnetic property sharply and produce a profound impact on the potential applications. The magnetic‐electric materials owned profound applications such as energy transfer and the control of magnetic‐electric devices …”

Section: Introductionmentioning

confidence: 99%

“…The research on the relationship between the strain and spin effect in magnetic-electric thin films has been widely studied worldwide; [1][2][3][4][5][6] the strain in the thin films could influence the magnetic property sharply and produce a profound impact on the potential applications.…”

Section: Introductionmentioning

confidence: 99%

The fabrication of layer‐by‐layer mode LaCoO₃ film by pulsed laser deposition

Liu

2017

Surface & Interface Analysis

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The relationship between strain and growth conditions in LaCoO3 thin film was obtained to control the magnetic‐electric characteristics. The LaCoO3 thin films on the SrTiO3 substrates have been achieved by the pulsed laser deposition method, and the reflection high‐energy electron diffraction method (RHEED) was applied to monitor the growth process in situ; the layer‐by‐layer growth mode was discovered. The X‐ray diffraction and atomic force microscopy were applied to the phase analysis, and the layer thickness and the layer‐by‐layer growth mode were uncovered. Compared with the 100‐nm LaCoO3 thin films, the strain in the layer‐by‐layer ultra thin film was more controllable. The enhanced magnetic properties of the layer‐by‐layer mode ultra‐thin films could be tested in future work.

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“…Because the built-in electric field pushes the electrons to the same side of the well for all states, a larger dipole strength and a larger energy interval can be obtained, which results in that the resonant peak of the absorption coefficient occurs at the high-energy direction, i.e., suffers a blue-shift [15], and the magnitude of the absorption peak also increases [17]. Moreover, the electric field in the well, the confined energy and the spatial distribution of electrons greatly differ for QWs with different well thicknesses [18]. Therefore, we expect that the intersubband optical absorption in the AlGaN/GaN QW can be modulated by the well thickness.…”

Section: Introductionmentioning

confidence: 99%

Effect of Well Thickness on the Intersubband Optical Absorptions in AlGaN/GaN/AlGaN Quantum Wells

Fang

et al. 2012

2012 Symposium on Photonics and Optoelectronics

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By solving the Schrödinger and Poisson equations selfconsistently for AlGaN/GaN QWs, we calculate the intersubband optical absorption coefficients for QWs with various well thicknesses. By increasing the well thickness, the amplitude of the dipole matrix increases slowly. However, the decrease of the energy separation results in the red-shift of the resonant absorption peak and the decrease of the magnitude of the absorption peak. Moreover, when the well thickness decreases to 10 Å, the evident decrease of the overlap between wave functions for the first two subbands leads to the abrupt decrease of the amplitude of the dipole matrix and the absorption peak. These results indicate that the intersubband optical absorption can be greatly modulated by the well thickness, the built-in electric field has an important effect on the intersubband absorption coefficients in III-nitride QWs, and III-nitride QWs are potential candidates for the design and application of intersubband devices.

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Effect of well thickness on the Rashba spin splitting and intersubband spin–orbit coupling in AlGaN/GaN/AlGaN quantum wells with two subbands

Cited by 13 publications

References 21 publications

Spin-orbit coupling in wurtzite heterostructures

Spin-orbit coupling in wurtzite heterostructures

The fabrication of layer‐by‐layer mode LaCoO₃ film by pulsed laser deposition

Effect of Well Thickness on the Intersubband Optical Absorptions in AlGaN/GaN/AlGaN Quantum Wells

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Effect of well thickness on the Rashba spin splitting and intersubband spin–orbit coupling in AlGaN/GaN/AlGaN quantum wells with two subbands

Cited by 13 publications

References 21 publications

Spin-orbit coupling in wurtzite heterostructures

Spin-orbit coupling in wurtzite heterostructures

The fabrication of layer‐by‐layer mode LaCoO3 film by pulsed laser deposition

Effect of Well Thickness on the Intersubband Optical Absorptions in AlGaN/GaN/AlGaN Quantum Wells

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Product

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The fabrication of layer‐by‐layer mode LaCoO₃ film by pulsed laser deposition