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Polarization and third-order Hall effect in III-V semiconductor heterojunctions

Ojasvi Pal and Tarun Kanti Ghosh
Phys. Rev. B 109, 035202 – Published 16 January 2024

Abstract

We study Berry connection polarizability (BCP) induced electric polarization and the third-order Hall (TOH) effect in a two-dimensional electron/hole gas (2DEG/2DHG) with Rashba-Dresselhaus (RD) spin-orbit couplings in III-V semiconductor heterostructures. The electric polarization decreases with increase of the Fermi energy and is responsive to the electric field orientation in the presence of RD spin-orbit couplings for both systems. We determine the BCP-induced TOH conductivity (χI) along with the TOH conductivity associated with the band velocity (χII). We find that the presence of an infinitesimal amount of Dresselhaus coupling in addition to the dominant Rashba coupling results in finite TOH responses. These conductivities vanish when the field is aligned with and/or orthogonal to the symmetry lines kx±ky=0 in both the systems. For typical system parameters in a 2DEG with k-linear RD interactions, the magnitude of χI is smaller than that of χII. On the other hand, when both the SO couplings are comparable, χI shows a notable increase in magnitude, owing to the distinctive characteristics of BCP. The TOH conductivity of 2DEG remains unchanged when Rashba and Dresselhaus spin-orbit couplings are exchanged. For 2DHG with k-cubic RD interactions, χI,h exhibits a larger magnitude compared to χII,h. Unlike the electron case, the BCP-induced χI,h alters under the exchange of spin-orbit coupling parameters, whereas χII,h remains the same.

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  • Received 31 October 2023
  • Revised 1 January 2024
  • Accepted 4 January 2024

DOI:https://doi.org/10.1103/PhysRevB.109.035202

©2024 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Ojasvi Pal and Tarun Kanti Ghosh

  • Department of Physics, Indian Institute of Technology-Kanpur, Kanpur 208016, India

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Vol. 109, Iss. 3 — 15 January 2024

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Images

  • Figure 1
    Figure 1

    Fermi contours along with the two mirror symmetric lines ky=±kx of a 2DEG with k-linear Rashba-Dresselhaus spin-orbit couplings for (a) αβ and (b) α=β. Here, kx and ky are plotted in units of k0.

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  • Figure 2
    Figure 2

    We present density plots of the band geometric quantities and the field-induced Berry curvature of the 2DEG with linear Rashba-Dresselhaus spin-orbit interactions. Top panels: α=6×109eV cm and β=1×109eV cm. Bottom panels: α=6×109eV cm and β=5×109eV cm. Here, [(a)–(c)] and [(f)–(h)] display the density plots of the BCP tensor components (in units of e/αk03); [(d)–(e)] and [(i)–(j)] display the field-induced Berry curvature Ωz(1) (in units of eE/αk04) for two orientations of the electric field along the y and x directions, respectively. The plots are given for the upper (+) band. We consider me=0.024m0, where m0 is the free electron mass [38]. In both panels, kx and ky are in units of k0.

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  • Figure 3
    Figure 3

    Polarization (in units of P0=e2E/ε0) as a function of angle θ for different Dresselhaus coupling strengths (in units of 109eV cm) at a fixed Rashba coupling strength of α=6×109eV cm: (a) εF>0 at a fixed electron density of ne=5.7×1010/cm2 and (b) εF<0 at ne=1010/cm2. The other parameters used are the same as in Fig. 2.

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  • Figure 4
    Figure 4

    Variation of the transverse third-order conductivities with angle θ for different Dresselhaus coupling strengths, while keeping the Rashba coupling strength fixed at α=6×109eV cm. The conductivities χI and χII correspond to transverse third-order conductivities proportional to τ and τ3, respectively. The total transverse conductivity is given by χ=χI+χII. The top panel [(a)–(c)] represents the case for εF>0, and the bottom panel [(d)–(f)] corresponds to the scenario where εF<0. The normalization parameters for conductivities, χI and χII, are given by χ1=τe44/me3α4 and χ2=e4τ3/me2, respectively. The value of β is given in units of 109eV cm. The β=5 curve is scaled by factors of 50 in (a) and 5 in (b) and (c), while the β=3 curve is scaled down by factors of 5 in (d) and (f). The parameters used are the same as in Fig. 3.

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  • Figure 5
    Figure 5

    Fermi contours along with the two mirror symmetric lines ky=±kx of the 2DHG with k-cubic Rashba-Dresselhaus spin-orbit couplings for (a) αhβh and (b) αh=βh. Here, kx and ky are plotted in units of kh.

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  • Figure 6
    Figure 6

    Distribution of the BCP tensors and the field-induced Berry curvature for + branch of a 2DHG with k-cubic Rashba-Dresselhaus spin-orbit interactions. Top panel: αh=0.1eV nm3 and βh=0.6αh. Bottom panel: αh=0.1eV nm3 and βh=0.9αh. Here, [(a)–(c)] and [(f)–(h)] represent the density plots of the BCP tensor components (in units of e/αhkh5); [(d)–(e)] and [(i)–(j)] represent the field-induced Berry curvature Ωz(1) (in units of eE/αhkh6) for two orientations of the electric field along the y and x directions, respectively. In both panels, kx and ky are plotted in units of kh. We consider mh=0.41m0, where m0 is the free electron mass.

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  • Figure 7
    Figure 7

    Polarization (in units of Ph=e2E/εh) for a hole gas with angle θ for different Dresselhaus coupling strengths (given in units of eV nm3) at a fixed Rashba coupling strength αh=0.1eV nm3. The other parameters used are charge carrier density nh=2×1015m2 and mh=0.41m0 [47].

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  • Figure 8
    Figure 8

    [(a)–(c)] Variation of the transverse third-order conductivities for the heavy-hole gas with k-cubic Rashba-Dresselhaus spin-orbit interactions as a function of the angle θ between the electric field and the x axis. The conductivities χI,h and χII,h represent the transverse third-order conductivities of the hole gas proportional to τ and τ3, respectively. The total transverse conductivity is given by χh=χI,h+χII,h. In (b), χII,h (αh=0.1 and βh=0.06) = χII,h (βh=0.1 and αh=0.06). The normalization parameters for conductivities, χI,h and χII,h, are given by χ1h=τe4mh5α4/12 and χ2h=e4τ3/mh2, respectively. The values of αh and βh are given in units of eV nm3. The parameters used are the same as in Fig. 7.

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