Influence Of Spin-orbit Interaction Research Articles

Electronic structure of zaykovite Rh3Se4, prediction, and analysis of physical properties of related materials: Pd3Se4, Ir3Se4, and Pt3Se4.

In this work, we explore the electronic properties and chemical bonding in the recently discovered mineral zaykovite, the first natural rhodium selenide Rh3Se4. We comprehensively studied the bulk electronic structure, hybridization of rhodium and selenium orbitals, and the influence of spin-orbit interaction on the electronic spectrum, as well as inspected its topological properties. In addition, we investigated the surface electronic structure of zaykovite and revealed the anisotropic Rashba-type spin splitting in the surface states. In addition, using calculations of the phonon spectra and enthalpy of formation, we predicted the family of similar selenides based on other 4d and 5d transition metals such as Ir, Pd, and Pt. The structural and electronic properties of these materials are discussed.

L -gap surface resonance at Pt(111): Influence of atomic structure, d bands, and spin-orbit interaction

Pt(111) hosts a surface resonance with peculiar properties concerning energy vs momentum dispersion and spin texture. At variance with the free-electron-like behavior of the L-gap Shockley-type surface states on the fcc(111) surfaces of Au, Ag, and Cu, it splits into several branches with distinct spin polarization around the center of the surface Brillouin zone Γ¯. Theoretical predictions based on density-functional theory vary depending on the particular functionals used. To clarify this issue, we investigate the atomic structure of Pt(111) by low-energy electron diffraction and the unoccupied electronic structure by spin- and angle-resolved inverse photoemission. The experimental results are backed by theoretical studies using different functionals, which show that the characteristics of the surface band depend critically on the lattice constant. From the analysis of the energy-dependent low-energy electron diffraction intensities, we derive structural parameters of the Pt(111) surface relaxation with high accuracy. In addition, we give an unambiguous definition of the nonequivalent mirror-plane directions Γ¯M¯ and Γ¯M¯′ at fcc(111) surfaces, which is consistent with band-structure calculations and inverse-photoemission data. Concerning the surface resonance at the bottom of the L gap, we identified a delicate interplay of several contributions. Lattice constant, hybridization with d bands, and the influence of spin-orbit interaction are critical ingredients for understanding the peculiar energy dispersion and spin character of the unoccupied surface resonance. Published by the American Physical Society 2024

Effect of spin-orbit coupling and impurities on the optical properties of double quantum rings under magnetic fields

In this paper, the energy spectrum of concentric double quantum rings (CDQRs) with double well confinement under the influence of spin-orbit interactions (SOIs), magnetic fields, and hydrogen donor impurities is studied by using diagonalization. The light absorption coefficient is then calculated in the form of a compactness density-matrix. Key findings from this study include the ability to manipulate fine energy level splitting and optical absorption coefficients by tuning the magnetic field, impurity position, spin-orbit coupling, and inner rings size. Furthermore, this study reveals the bleaching effect of the optical absorption coefficient under certain conditions and demonstrates the anisotropic nature of the system through changes in the optical absorption coefficients (OACs) for different incident light polarization angles.

Theoretical description of the decay width of neutron emission in light nuclei

<p indent="0mm">The study of nuclear decay is an important field for investigating nuclear structures and nucleosynthesis. The existence of Coulomb interaction makes the emission of charged particles have a relatively long half-life. Based on the WKB approximation and the R-matrix method, several empirical formulas describing the proton decay, alpha decay, and emission of charged clusters have been proposed, e.g., the new Geiger-Nutall formula and the Universal Decay Law. The investigation of beta delayed proton(s) decay enhances understanding of isospin symmetry breaking and mixing. Because of the absence of Coulomb interaction, the half-life of neutron emission is much shorter. For neutron-unbound states, the experimentalists concentrate more on discovering neutron-rich nuclei beyond the neutron-drip line. The theorists are more interested in establishing models for a specific nucleus to describe the one- and two-neutron emission phenomenon. The universal law describing the general characteristics of single neutron emission is rarely taken into account. This paper applies the WKB approximation and the R-matrix method to investigate the decay width of the single neutron emission. The square well potential and the harmonic oscillator potential are used as input of nuclear potential. As to the R-matrix method, the sine function basis and the Lagrange basis are applied, respectively. Both the WKB approximation and the R-matrix method calculate the decay width in two parts: The formation factor and the penetration factor. A three-variable formula is deduced from the penetration factor of these two theories. As to the ground states emitting a single neutron, the root-mean-square of log₁₀<italic>Γ</italic>_exp/<italic>Γ</italic>_cal for the three-variable formula is only 0.31, which shows a good description ability. The decay widths of the other 13 nuclides are thus predicted. For the excited states, the direct application of the two theories presents deviation within an order of about 3. The decay width is found to be sensible to the radius of nuclear force and less sensible to the depth of nuclear potential according to the comparison between the square well potential and the harmonic oscillator potential. The hard-core effect is intrinsically considered by the R-matrix method, compared with the WKB approximation, which shows an overall overestimation. After removing such an overestimation, the deviation of the WKB approximation is reduced to be in the order of about 0.8. The three-variable formula shows better description capability, and the deviation is reduced to be in the order of 0.56. The suggested formula is the first try to describe the decay width of a single neutron emission well, which is beneficial to further investigate the characteristics of nuclei near the neutron drip line. Moreover, the influence of spin-orbit interaction, the tensor force, and the shell effect can be taken into account for amelioration. Besides, the fission products of heavy nuclei are generally in highly excited states and will be deexcited through beta decay, emitting neutrons, etc. The neutron emission and beta-delayed neutron emission in these processes are important for the chain reaction and the control of the nuclear reactor. For further investigation, the results of this paper will be extended and applied to the region of nuclear fission products.

Rashba-split image-potential state and unoccupied surface electronic structure of Re(0001)

The influence of spin-orbit interaction on the unoccupied electronic structure of the Re(0001) surface is investigated by spin- and angle-resolved inverse photoemission and density-functional theory calculations. In the two high-symmetry azimuths $\overline{\mathrm{\ensuremath{\Gamma}}}\phantom{\rule{0.16em}{0ex}}\overline{\text{K}}$ and $\overline{\mathrm{\ensuremath{\Gamma}}}\phantom{\rule{0.16em}{0ex}}\overline{\text{M}}$, we identify transitions into $d$-derived bulk states as well as different types of surface states. The Rashba-type spin-split hole pocket around $\overline{\mathrm{\ensuremath{\Gamma}}}$ finds continuation in empty spin-split surface states for higher ${\mathbf{k}}_{\ensuremath{\parallel}}$, thereby forming $\mathsf{W}$-shaped states whose lower parts are partially occupied. A large energy gap below and above the vacuum energy around $\overline{\mathrm{\ensuremath{\Gamma}}}$ hosts image-potential-induced surface states. The $n=1$ member of the Rydberg-like series exhibits a free-electron-like $E({\mathbf{k}}_{\ensuremath{\parallel}})$ dispersion with an effective mass of ${m}^{*}/{m}_{e}=1.2\ifmmode\pm\else\textpm\fi{}0.1$. Careful spin-resolved measurements for several angles of electron incidence allow us to detect Rashba-type spin-dependent energy splittings of this state with a Rashba parameter of ${\ensuremath{\alpha}}_{\text{R}}=105\ifmmode\pm\else\textpm\fi{}33\phantom{\rule{0.16em}{0ex}}\text{meV}\phantom{\rule{0.16em}{0ex}}\AA{}$.

Two-dimensional hydrogen-like atom in magnetic field in the presence of Rashba spin–orbit coupling

Abstract We investigate the spin–orbit (SO) Rashba coupling effect on bound states of an electron confined to the two-dimensional (2D) hydrogen-like atom (TDHA) in the presence of an external magnetic field (B), applied perpendicularly to the atomic plane. Energy levels and wavefunctions for arbitrary B and SO Rashba coupling constant have been obtained by the diagonalization of the Schrodinger Hamiltonian with the SO Rashba coupling term, using the basis of discrete Coulomb Sturmian functions. The solutions are used to investigate the influence of the SO Rashba interaction on phase coherence of spin states in terms of the von Neumann (vN) entropy and the spin polarization of the system. We shown that there exists unique correspondence between the vN spin entropy and the magnitude of spin-polarization vector. We also study the influence of SO interaction on magnetic properties of the planar H-like exciton using parameters appropriate for InSb semiconductor nanostructure.

The influence of spin orbit interaction on phonons and superconductivity in the noncentrosymmetric superconductors LaPt3Si and LaPtSi3

We have performed ab initio study of structural, electronic, vibrational and electron-phonon interaction properties of LaPt3 Si and LaPtSi3 by employing the density functional theory, a linear-response formalism, and the plane-wave pseudopotential method. The electronic structure, phonon dispersion relations and the Eliashberg spectral function for these materials have been examined with and without the inclusion of spin-orbit interaction (SOI). Our electron-phonon interaction results reveal that the influence of spin-orbit interaction on phonons and superconductivity in these noncentrosymmetric superconductors is very small. Thus, we can conclude that a mixing of the spin-singlet and the spin-triplet components in these superconductors is weak and the spin-singlet Cooper pairs dominate. By integrating the Eliashberg spectral function α2F(ω), the average electron-phonon coupling parameter λ is obtained to be 0.470 for LaPt3 Si and 0.488 for LaPtSi3, indicating these to be weak-coupling BCS superconductors. Using an acceptable value of μ∗ = 0.13 for the effective Coulomb repulsion parameter, the superconducting critical temperature Tc is calculated to be 0.67 K for LaPt3 Si and 1.39 K for LaPtSi3, in good accordance with experimental values of 0.65 K and 1.52 K, respectively.

Influence of spin-orbit interaction within the insulating barrier on the electron transport in magnetic tunnel junctions

We present a theory of the anisotropy of tunneling magnetoresistance (ATMR) phenomenon in magnetic tunnel junctions (MTJs) attributed to Rashba spin-orbit interaction in the insulating barrier. ATMR represents the difference of tunnel magnetoresistance (TMR) amplitude measured with in-plane and out-of-plane magnetic configurations. It is demonstrated that within the spin-polarized free-electron model the change of conductance associated with the ATMR is exactly twice the change of conductance measured at full saturation (i.e., in parallel configuration of magnetizations) between in-plane and out-of-plane configuration, i.e., the tunneling anisotropic magnetoresistance (TAMR). Both ATMR and TAMR are closely related to the TMR amplitude and spin-orbit constant. The predicted ATMR phenomenon is confirmed experimentally, showing a few percent value in the case of the widely studied CoFeB/MgO/CoFeB based MTJ.

Investigation of electro-optical properties of InSb under the influence of spin-orbit interaction at room temperature

To investigate the electro-optical properties of indium antimonide (InSb) for photo-voltaic applications, we performed first principles calculations using density functional theory (DFT). Our DFT calculations are based on full potential linearized augmented plane wave (FP-LAPW) method implemented by WIEN2K code. These calculations are carried out using generalized gradient approximation (GGA) and Tran Blaha modified Becke Johnson (TB-mBJ) approximation for exchange co-relation potential. All the calculations are performed with and without the addition of spin-orbit interaction (SOI) to GGA and TB-mBJ potentials. Addition of SOI gives the results very close to their experimental values and makes the calculations independent of k-points consideration. All the results are calculated by considering the temperature as high as 300 K. To the best of our knowledge, all the previously published theoretical results were calculated at 0 K and no such results have been reported at 300 K. In this article, we are reporting band structure, density of states (DOS) and the band gap dependent optical properties of InSb. The calculated direct band gap is 0.17 eV, refractive index is 3.79 and extinction coefficient as 3.22.

Kondo effect in a quantum wire with spin-orbit coupling

The influence of spin-orbit interactions on the Kondo effect has been under debate recently. Studies conducted recently on a system composed by an Anderson impurity on a 2DEG with Rashba spin-orbit have been shown that it can enhance or suppress the Kondo temperature ($T_{\rm K}$), depending on the relative energy level position of the impurity with respect to the particle-hole symmetric point. Here we investigate a system composed by a single Anderson impurity side-coupled to a quantum wire with spin-orbit coupling (SOC). We derive an effective Hamiltonian in which the Kondo coupling is modified by the SOC. In addition, the Hamiltonian contains two other scattering terms, the so called Dzaloshinskyi-Moriya interaction, know to appear in these systems, and a new one describing processes similar to the Elliott-Yafet scattering mechanisms. By performing a renormalization group analysis on the effective Hamiltonian, we find that the correction on the Kondo coupling due to the SOC favors and enhancement of the Kondo temperature even in the particle-hole symmetric point of the Anderson model, agreeing with the NRG results. Moreover, away from the particle-hole symmetric point, $T_{\rm K}$ always increases with the SOC, accordingly with the previous renormalization group analysis.

The effect of spin-orbit interaction on the electron spin transport in inorganic semiconductors and the comparison of organic semiconductors

In theory, the influence of spin-orbit interaction on the electron spin transport in inorganic semiconductors was discussed, which was compared with that of organic semiconductors. Results reveal that the internal mechanism of spin precession in inorganic semiconductor is different from that of the organic semiconductor, while the influence of the spin-orbit interaction on the carrier spin transport is same.

Spin-orbit influence ondz2-type surface state at Ta(110)

The influence of spin-orbit interaction on an occupied surface state at Ta(110) is investigated with spin-and angle-resolved photoemission and electronic structure calculations. The surface state a ...

Asymmetric ferromagnetic resonance, universal Walker breakdown, and counterflow domain wall motion in the presence of multiple spin-orbit torques

We study the motion of several types of domain wall profiles in spin-orbit coupled magnetic nanowires and also the influence of spin-orbit interaction on the ferromagnetic resonance of uniform magnetic films. Whereas domain wall motion in systems without correlations between spin space and real space is not sensitive to the precise magnetization texture of the domain wall, spin-orbit interactions break the equivalence between such textures due to the coupling between the momentum and spin of the electrons. In particular, we extend previous studies by fully considering not only the fieldlike contribution from the spin-orbit torque, but also the recently derived Slonczewski-like spin-orbit torque. We show that the latter interaction affects both the domain wall velocity and the Walker breakdown threshold nontrivially, which suggests that it should be accounted for in experimental data analysis. We find that the presence of multiple spin-orbit torques may render the Walker breakdown universal in the sense that the threshold is completely independent on the material-dependent Gilbert damping $\ensuremath{\alpha}$, nonadiabaticity $\ensuremath{\beta}$, and the chirality $\ensuremath{\sigma}$ of the domain wall. We also find that domain wall motion against the current injection is sustained in the presence of multiple spin-orbit torques and that the wall profile will determine the qualitative influence of these different types of torques (e.g., fieldlike and Slonczewski-like). In addition, we consider a uniform ferromagnetic layer under a current bias, and find that the resonance frequency becomes asymmetric against the current direction in the presence of Slonczewski-like spin-orbit coupling. This is in contrast with those cases where such an interaction is absent, where the frequency is found to be symmetric with respect to the current direction. This finding shows that spin-orbit interactions may offer additional control over pumped and absorbed energy in a ferromagnetic resonance setup by manipulating the injected current direction.

Chirality-sensitive domain wall motion in spin-orbit coupled ferromagnets

Using the Lagrangian formalism, we solve analytically the equations of motion for current-induced domain-wall dynamics in a ferromagnet with Rashba spin-orbit coupling. An exact solution for the domain wall velocity is provided, including the effect of non-equilibrium conduction electron spin-density, Gilbert damping, and the Rashba interaction parameter. We demonstrate explicitly that the influence of spin-orbit interaction can be qualitatively different from the role of non-adiabatic spin-torque in the sense that the former is sensitive to the chirality of the domain wall whereas the latter is not: the domain wall velocity shows a reentrant behavior upon changing the chirality of the domain wall. This could be used to experimentally distinguish between the spin-orbit and non-adiabatic contribution to the wall speed. A quantitative estimate for the attainable domain wall velocity is given, based on an experimentally relevant set of parameters for the system.

Mass enhancement parameter in free-standing ultrathin Pb(111) films: The effect of spin-orbit coupling

The influence of spin-orbit interaction on the electron-phonon coupling strength at the Fermi level of thin lead films is investigated using first-principles calculations in the density functional perturbation formalism. The calculations both scalar relativistic and including spin-orbit coupling (SOC) have been carried out for free-standing Pb(111) films consisting of four to ten atomic layers. It is shown that the spin-orbit interaction produces a large enhancement of the electron-phonon coupling strength regardless of the film thickness. This partly reflects a strong SOC-induced softening of the film phonon spectra, and partly a SOC-mediated increase in electron-phonon coupling matrix elements. For thin films, quantum size effects result in pronounced oscillations of the average coupling constant with the number of layers, which become damped for thicker films.

First-Principles Study on Half-Metallic Full-Heusler Compound Mn2ZnSi

By first-principle calculation, the electronic structure and magnetic properties of the Mn2ZnSi full-Heusler alloy with CuHg2Ti-type structure are investigated. Calculations show that Mn2ZnSi compound presents half-metallic ferrimagnetic properties under the equilibrium lattice constant. The influence of spin-orbit interaction for the magnetic moments is investigated. The result shows spin-orbit interaction has little influence on magnetic moment. The bulk modulus of Mn2ZnSi obtained by a fit of the Murnaghan equation of state is 134.3 GPa, which is more compressible than some other Heusler alloys. At the pressure range of 0 to 17.7 GPa, Mn2ZnSi presents half-metallic character. Mn2ZnSi would be a promising material for future spintronic applications.

Quasiparticle velocities in two-dimensional electron/hole liquids with spin-orbit coupling

We study the influence of spin-orbit interactions on quasiparticle dispersions in two-dimensional electron and heavy-hole liquids in III-V semiconductors. To obtain closed-form analytical results, we restrict ourselves to spin-orbit interactions with isotropic spectrum and work within the screened Hartree-Fock approximation, valid in the high-density limit. For electrons having a linear-in-momentum Rashba (or, equivalently, Dresselhaus) spin-orbit interaction, we show that the screened Hartree-Fock approximation recovers known results based on the random-phase approximation and we extend those results to higher order in the spin-orbit coupling. While the well-studied case of electrons leads only to a weak modification of quasiparticle properties in the presence of the linear-in-momentum spin-orbit interaction, we find two important distinctions for hole systems (with a leading nonlinear-in-momentum spin-orbit interaction). First, the group velocities associated with the two hole-spin branches acquire a significant difference in the presence of spin-orbit interactions, allowing for the creation of spin-polarized wavepackets in zero magnetic field. Second, we find that the interplay of Coulomb and spin-orbit interactions is significantly more important for holes than for electrons and can be probed through the quasiparticle group velocities. These effects should be directly observable in magnetotransport, Raman scattering, and femtosecond-resolved Faraday rotation measurements. Our results are in agreement with a general argument on the velocities, which we formulate for an arbitrary choice of the spin-orbit coupling.

Simultaneous effects of spin-orbit interaction and external electric field on the linear and nonlinear optical properties of a cubic quantum dot

In this article simultaneous effects of external electric field and spin-orbit interaction on the linear and the nonlinear optical properties of a cubic quantum dot are studied. Based on the non- degenerate perturbation method, energy eigenvalues and eigenfunctions of the system under the influence of spin-orbit interaction are calculated. Furthermore, the linear and the nonlinear optical absorption coefficients and refractive index changes are obtained using the compact density matrix approach and iterative method. Our results show that, due to the spin-orbit interaction, resonant peak values of the optical absorption coefficients and refractive index changes decrease and occur at lower values of the incident photon energy. The variation of these optical parameters depend on the spin-orbit interaction strength, dot dimensions and external electric field.

Influence of Spin-Orbit Interaction on Band Structure and Elastic Properties of PbTe

Influence of Spin-Orbit Interaction on Band Structure and Elastic Properties of PbTe

Quantitative evaluation of spin-orbit interaction in InAs quantum dots

Influence of spin-orbit interaction (SOI) on the energy spectrum is studied for single uncapped InAs self-assembled quantum dots (SAQDs) holding just a few electrons. We measure Coulomb oscillations with magnetic field, and identify lifting of spin doublets in the low field range and transitions in the ground states with keeping the total angular momentum in the high field range. Both of these features are induced by large Zeeman splitting in the present SAQDs. For the ground state transitions, anti-crossing due to the SOI hybridization between the ground and excited states with opposite spins is observed in the excitation spectra, and the SOI energy of about 0.1 meV is evaluated from the anti-crossing size. This energy is comparable to that of previous report on InAs nanowires, and reproduced by simple calculation using the g-factor also derived in the excitation spectra.