Observation of a cubic Rashba effect in the surface spin structure of rare-earth ternary materials
D. Yu. Usachov, I. A. Nechaev, G. Poelchen, M. Güttler, E. E. Krasovskii, S. Schulz, A. Generalov, K. Kliemt, A. Kraiker, C. Krellner, K. Kummer, S. Danzenbäche… 展开作者
D. Yu. Usachov, I. A. Nechaev, G. Poelchen, M. Güttler, E. E. Krasovskii, S. Schulz, A. Generalov, K. Kliemt, A. Kraiker, C. Krellner, K. Kummer, S. Danzenbächer, C. Laubschat, A. P. Weber, E. V. Chulkov, A. F. Santander-Syro, T. Imai, K. Miyamoto, T. Okuda, D. V. Vyalikh
Spin-orbit interaction and structure inversion asymmetry in combination with magnetic ordering is a promising route to novel materials with highly mobile spin-polarized carriers at the surface. Spin-resolved measurements of the photoemission current from the Si-terminated surface of the antiferromagnet TbRh2Si2 and their analysis within an ab initio one-step theory unveil an unusual triple winding of the electron spin along the fourfold-symmetric constant energy contours of the surface states. A two-band k.p model is presented that yields the triple winding as a cubic Rashba effect. The curious in-plane spin-momentum locking is remarkably robust and remains intact across a paramagnetic-antiferromagnetic transition in spite of spin-orbit interaction on Rh atoms being considerably weaker than the out-of-plane exchange field due to the Tb 4f moments.
The anomalous Hall and Nernst effects are considered theoretically within Matsubara-Green's function formalism. The effective Hamiltonian of a magnetized two-dimensional electron gas with cubic Rashba spin-orbit interaction may describe transport properties of electronic states at the interfaces or surfaces of perovskite oxides or another type of heterostructures that, due to symmetry, may be described by the same effective model. In the quasi-ballistic limit, both effects are determined by the topological (Fermi sea) contribution whereas the states at the Fermi level gives a negligibly small …
Generating and controlling spin current (SC) are of central interest in spin physics and applications. To date, the spin-orbit interaction (SOI) is an established pathway to generate SC through the spin-charge current conversion. We predict an efficient spin-light conversion via the Rashba and higher-order cubic Dresselhaus SOIs in ferroelectrics. Different from the known Edelstein effect, where SC is created by the nonequilibrium spin density, our predicted spin-polarized current is from direct interactions between light and unique spin textures generated by SOI in ferroelectrics. Using first…
The interaction between the linear and cubic spin-orbit coupling with magnetic moments and mobile spin-polarized carriers in the LaO/STO system provides new avenues for spin transport applications. We study the interplay between linear and cubic Rashba spin orbit coupling (RSOC) on in-plane magnetic moments in the LaO/STO system using the Boltzmann transport theory based on the relaxation time approximation (RTA) and the more refined Schliemann-Loss (SL) delta-potential scattering model. In general, both methods yield a linear (quadratic) relationship between the spin accumulation (spin curren…
It is well known that the Dresselhaus spin-orbit coupling (SOC) in semiconductor two dimensional electron gases (2DEGs) possesses both linear and cubic in momentum contributions. Nevertheless, the latter is usually neglected in most theoretical studies. However, recent Kerr rotation experiments have revealed a significant enhancement of the cubic Dresselhaus interaction by increasing the drift velocities in 2DEGs hosted in GaAs quantum wells. Here, we present a study of the optical spin Hall conductivity in 2DEGs under the simultaneous presence of Rashba and (linear plus cubic) Dresselhaus SOC…
Spin-orbit interaction in semiconductor structures with broken space inversion symmetry leads to spin splitting of electron and hole states even in the absence of magnetic field. We discover that, beyond the Rashba and Dresselhaus contributions, there is an additional type of the zero-field spin splitting which is caused by the interplay of the cubic shape of crystal unit cell and macroscopic structure asymmetry. In quantum wells grown along low-symmetry crystallographic axes, this type of spin-orbit interaction couples the out-of-plane component of carrier's spin with the in-plane momentum wh…
We formulate the effective Hamiltonian of Rashba spin-orbit coupling (RSOC) in $\mathrm{LaAlO_3/SrTiO_3}$ (LAO/STO) heterostructures. We derive analytical expressions of properties, e.g., Rashba parameter, effective mass, band edge energy and orbital occupancy, as functions of material and tunable heterostructure parameters. While linear RSOC is dominant around the $Γ$-point, cubic RSOC becomes significant at the higher-energy anti-crossing region. We find that linear RSOC stems from the structural inversion asymmetry (SIA), while the cubic term is induced by both SIA and bulk asymmetry. Furth…
Our recent study [Phys. Rev. B 103, 085309 (2021)] verified the existence of $\bf{k}$-linear Rashba spin-orbit coupling (SOC) of two-dimensional hole gases in quantum wells (QWs) which originates from a combination of heavy-hole-light-hole (HH-LH) mixing and direct dipolar coupling to the external electric field. However, the Rashba SOC dependence on QW orientations remains unclear. Here, we explore this dependence on QW orientations and uncover an upper and lower bound to the orientation-dependent $\bf{k}$-linear Rashba SOC along the [110]- and [111]- crystalline directions by performing atom…
We derive a closed-form expression for the weak localization (WL) corrections to the magnetoconductivity of a 2D electron system with arbitrary Rashba $α$ and Dresselhaus $β$ (linear) and $β_3$ (cubic) spin-orbit interaction couplings, in a perpendicular magnetic field geometry. In a system of reference with an in-plane $\hat{z}$ axis chosen as the high spin-symmetry direction at $α= β$, we formulate a new algorithm to calculate the three independent contributions that lead to WL. The antilocalization is counterbalanced by the term associated with the spin-relaxation along $\hat{z}$, dependent…
Many modern spin-based devices rely on the spin-orbit interaction, which is highly sensitive to the host semiconductor heterostructure and varies substantially depending on crystal direction, crystal asymmetry (Dresselhaus), and quantum confinement asymmetry (Rashba). One-dimensional quantum point contacts are a powerful tool to probe both energy and directional dependence of spin-orbit interaction through the effect on the hole $g$-factor. In this work we investigate the role of cubic crystal asymmetry in driving an oscillation in the in-plane hole $g$-factor anisotropy when the quantum point…
Two-dimensional hole gases in semiconductor quantum wells are promising platforms for spintronics and quantum computation but suffer from the lack of the $\bf{k}$-linear term in the Rashba spin-orbit coupling (SOC), which is essential for spin manipulations without magnetism and commonly believed to be a $\bf{k}$-cubic term as the lowest order. Here, contrary to conventional wisdom, we uncover a strong and tunable $\bf{k}$-linear Rashba SOC in two-dimensional hole gases (2DHG) of semiconductor quantum wells by performing atomistic pseudopotential calculations combined with an effective Hamilto…
Spin-orbit coupling in two-dimensional systems is usually characterized by Rashba and Dresselhaus spin-orbit coupling (SOC) linear in the wave vector. However, there is a growing class of materials which instead support dominant SOC cubic in the wave vector (cSOC), while their superconducting properties remain unexplored. By focusing on Josephson junctions in Zeeman field with superconductors separated by a normal cSOC region, we reveal a strongly anharmonic current-phase relation and complex spin structure. An experimental cSOC tunability enables both tunable anomalous phase shift and supercu…
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$\times$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 e…
Theory of the inverse spin galvanic effect in quantum wells
理解自旋和电荷密度以及通过自旋-轨道耦合的电流相互转换的基本原理可以使传统电子学提供的可能性之外的有效应用成为可能。为此，我们考虑了半导体量子阱和外延层中各种形式的频率相关的逆自旋电流效应（ISGE），考虑了Rashba和Dresselhaus形式中电子动量自旋轨道耦合的立方，集中于电流诱导的自旋极化（CISP）。我们发现，包括立方项定性地解释了最近的研究结果的CISP在InGaAs外延层是最强的，如果内部自旋轨道耦合场是最小的，反之亦然（诺曼等。2014，Luengo et al. 2017），与一般理解相反。我们的研究结果提供了一个很有前途的框架控制自旋输运在未来的自旋电子器件。
In a semiconductor, collective excitations of spin textures usually decay rather fast due to D'yakonov-Perel' spin relaxation. The latter arises from spin-orbit coupling, which induces wave-vector-dependent spin rotations that, in conjunction with random disorder scattering, generate spin decoherence. However, symmetries occurring under certain conditions can prevent the relaxation of particular homogeneous and inhomogeneous spin textures. The inhomogeneous spin texture, termed as persistent spin helix, is especially appealing as it enables us to manipulate the spin orientation while retaining…
