Spin-orbit interactions in heterocyclic analogues of fluorene

For carbazole, dibenzofuran, and dibenzothiophene—heterocyclic analogues of fluorene containing N-H, O, and S groups, respectively—the transition dipole moments P ₀₀ ⁱ for the transitions ³ B ₂→S ₀ and ³ A ₁→S ₀ from the sublevels i=z, y, x of the triplet electronic ππ* states, which are caused by intramolecular spin-orbit (SO) interactions, are calculated. The effect that the SO coupling between the S ₀ state and highest triplet states has on the calculation results is considered. The effects exerted on the value of P ₀₀ ⁱ by such specific features of the molecular structure as the position of a heteroatom on the symmetry axis, its valence, and different constants of SO coupling in heteroatoms are discussed. The reason for the weak influence of the quantity ?_HA on the rate constant of radiative deactivation of the lowest T state is ascertained.     

Vibronic-spin-orbit interactions in heterocyclic analogues of fluorene with the N and O heteroatoms

The transition dipole moments P _0n ^s for the transitions from the electronic triplet state ³ B ²(ππ*) to vibrational sublevels of the vibrational out-of-plane modes n of the carbazole and dibenzofuran molecules are calculated. The values of the radiative deactivation rate constant k _rad ^s of the triplet sublevels T ^s are determined along with the components k _SO ^s and k _VSO ^s of this constant, which depend on the intramolecular spin-orbit (SO) and vibronic-spin-orbit (VSO) interaction. It is ascertained that k _rad ^z > k _rad ^y . For different structural units of the molecules (the heteroatom and the carbon atoms of the dibenzene fragment), the effect of the SO coupling on the constant k _VSO～Σ_{s, n} (P _0n ^s )² is studied. A competition between the effects on k _VSO from the SO coupling in the carbon atoms and in the light N and O heteroatoms is revealed. This competition accounts for the weak influence of the heteroatom on this component of the rate constant k _rad in these molecules. It is ascertained that the intensity distribution among the vibronic lines in the phosphorescence spectra of carbazole and dibenzofuran I _0n ～Σs (P _0n ^s )² is different due to the substantially different influence of the N and O heteroatoms on the deactivation of the triplet sublevel T ^y .     

The effect of the heteroatom on the radiative deactivation of the lowest triplet state in heterocyclic analogues of fluorene

The vibronic transition strengths F _VSO ^s for the transitions from the spin sublevels s of the triplet state T₁ to the energy levels of the nontotally symmetric vibrations of dibenzothiophene (DB(S)) are calculated. For a series of heterocyclic analogues of fluorene (DB(S) and previously studied carbazole, dibenzofuran, and phenyldibenzophosphole), the regular features of the effect of the valence state of the heteroatom and of the spin-orbit interactions in individual atomic groups of the molecule are revealed. The factors affecting changes in the radiative deactivation rate constant of the T₁ state of the molecules studied are established. The intensity distribution of the vibronic lines in the Herzberg-Teller component of the fine structure phosphorescence spectrum of phenyldibenzophosphole is calculated taking into account different populations of the triplet sublevels.     

氦原子sp组态的自旋-轨道相互作用精细结构参数

本文借助不可约张量理论,导出了通常由光谱实验数据确定的氦原子sp组态自旋-轨道相互作用精细结构参数A的理论计算式,在推导过程中完成所有角向积分和自旋求和计算.     

Enhancement of the Kondo effect through Rashba spin-orbit interactions

We study a one-orbital Anderson impurity in a two-dimensional electron bath with Rashba spin-orbit interactions in the Kondo regime. The spin SU(2) symmetry-breaking term couples the impurity to a two-band electron gas. A Schrieffer-Wolff transformation shows the existence of the Dzyaloshinsky-Moriya interaction away from the particle-hole symmetric impurity state. A renormalization group analysis reveals a two-channel Kondo model with ferro- and antiferromagnetic couplings. The parity-breaking Dzyaloshinsky-Moriya term renormalizes the antiferromagnetic Kondo coupling with an exponential enhancement of the Kondo temperature.     

Hyperfine structure of a hydrogen-like atom due to orbit-orbit,spin-orbit,and spin-spin interactions

A nonrelativistic model of a hydrogen-like atom is considered. This model is used to calculate corrections to the energy spectrum of the atom. The analysis is based on a Hamiltonian that includes the intratomic fields generated by the electron and the nucleus.     

On the discrete spectrum of spin-orbit Hamiltonians with singular interactions

We give a variational proof of the existence of infinitely many bound states placed below the continuous spectrum for spin-orbit Hamiltonians (including the Rashba and Dresselhaus cases) perturbed by measure potentials, thus extending results of J. Brüning, V. Geyler, K. Pankrashkin, J. Phys. A: Math. Theor. 40 F113–F117 (2007).     

Wavevector filtering in graphene-based double junctions with the spin-orbit interactions

We show that the angle resolved transmission probability through the graphene-based double junctions with the spin-orbit interactions (SOIs) can be efficiently controlled by the SOIs strength, the parameter of the junctions, and the incident energy of the electron. It is anticipated to apply such a phenomenon to design an electron wavevector filter based on the graphene material by a pure electrical method.     

The effect of spin-orbit interaction on optical conductivity in graphene

We present a systematic investigation of the effect of spin-orbit interaction on optical conductivity in monolayer graphene. Our key findings are: (i) level splitting at various crystal symmetry points caused by true spin as well as pseudospin of the electrons gives rise to a resonant current response; (ii) under heavy doping, the spin-orbit interaction leads to a re-entrance of finite conductivity at very low frequency which was strictly forbidden in the absence of spin-orbit coupling; (iii) deformation of band structure and the topological properties of trigonal warping are analytically identified in a low-energy conical-like approximation.     

Aharonov-Bohm oscillations in the presence of strong spin-orbit interactions

We have measured highly visible Aharonov-Bohm (AB) oscillations in a ring structure defined by local anodic oxidation on a p-type GaAs heterostructure with strong spin-orbit interactions. Clear beating patterns observed in the raw data can be interpreted in terms of a spin geometric phase. Besides h/e oscillations, we resolve the contributions from the second harmonic of AB oscillations and also find a beating in these h/2e oscillations. A resistance minimum at B=0 T, present in all gate configurations, is the signature of destructive interference of the spins propagating along time-reversed paths.     

Ballistic spin interferometer based on the Rashba and Dresselhaus spin-orbit interactions

By using the Al'tshuler-Aronov-Spivak (AAS) model, we give the amplitude changing with Rashba spin-orbit interaction (SOI) and Dresselhaus SOI strength. In the first idea 1D square loop (SL), Rashba SOI acts on two sides while Dresselhaus SOI acts on the other two sides. In the second SL, we consume Rashba SOI and Dresselhaus SOI act on four sides simultaneously. This model can be replaced by another one that Rashba SOI and Dresselhaus SOI act on every side independently, and each side is twice long. We theoretically illustrate the influence of the Dresselhaus SOI on node position and number. To explain the “half oscillation” phenomenon found in experiment, we apply Dresselhaus SOI to the ideal 1D SL. The conclusion is that the Dresselhaus SOI has a strong effect on the emergence of “half oscillation”.     

Long-range interactions of the chlorine atom

The dispersion interactions of the chlorine atom ground state with atomic hydrogen and itself are computed with a matrix element tabulation derived from the box-based B-spline configuration-interaction method. The matrix element list was also used to calculate the quadrupole and octupole polarisabilities of the chlorine ground state.     

Influence of the spin-orbit coupling on the optical collision for Ba atom perturbed by rare gases

The quantum non-adiabatic theory of atomic collisions in the presence of a weak radiation field is applied to describe the Ba-rare-gas (RG) optical collision. The absorption coefficient as well as linear and circular polarizations of collisionally redistributed fluorescence light are calculated for a range of detuning around the barium (λ₃ = 5535Å) resonance line. Closecoupling calculations involving the relevant X¹Σ, ¹Σ,¹II, ³Σ and ³II states for each Ba-RG pair are carried out based on the new theoretical potential curves obtained by Czuchaj within the valence ab initio scheme. Our attention is mainly paid to the role of spin-changing transitions between the (6s6p) ¹P and (6s6p) ³P states in the process investigated. The numerical results show that the singlet-triplet mixing is important in the red-wing part of the spectra. The calculated absorption coefficients and polarizations are thermally averaged over the collision energy and compared with the experimental results of Alford et al. [1984, Phys. Rev. A, 30, 2366] and Ni et al. [1996, Z. Phys. D, 38, 303].     

On the influence of spin-orbit scattering on the Kondo effect

It is shown that the hyperfine splitting of the levels 2s _1/2 and 2p _1/2 of atomic hydrogen has a measurable influence on the mixing of these levels in a weak electric field.     

Model of the pair phosphorus atom-interstitial silicon atom

Interstitial defects in silicon implanted with P and Si ions are investigated by x-ray diffraction. It is established that the interstitial complexes formed by implantation and in subsequent heat treatment do not contain a P atom. A model is proposed for the pair PI: P atom-institial Si atom. The pair PI consists of P and Si atoms at the same interstice which are not bound to one another by a covalent bond. The pair model accounts for the characteristic features of the diffusion of implanted phosphorus in silicon. Fiz. Tverd. Tela (St. Petersburg) 40, 1995–1998 (November 1998)     

The effect of spin-orbit coupling on magnetoresistance in nonmagnetic organic semiconductors

We investigated the effect of spin-orbit coupling on magnetoresistance in nonmagnetic organic semiconductors.A Lorentz-type magnetoresistance is obtained from spin-orbit coupling-dependent spin precession under the condition of a space-charge-limited current.The magnetoresistance depends on the initial spin orientation of the electron with respect to the hole in electron-hole pairs,and the increasing spin-orbit coupling slows down the change in magnetoresistance with magnetic field.The field dependence,the sign and the saturation value of the magnetoresistance are composite effects of recombination and dissociation rate constants of singlet and triplet electron-hole pairs.The simulated magnetoresistance shows good consistency with the experimental results.     

The effects of Dresselhaus and Rashba spin-orbit interactions on the electron tunneling in a non-magnetic heterostructure

We theoretically investigate the electron transport properties in a non-magnetic heterostructure with both Dresselhaus and Rashba spin-orbit interactions. The detailed-numerical results show that (1) the large spin polarization can be achieved due to Dresselhaus and Rashba spin-orbit couplings induced splitting of the resonant level, although the magnetic field is zero in such a structure, (2) the Rashba spin-orbit coupling plays a greater role on the spin polarization than the Dresselhaus spin-orbit interaction does, and (3) the transmission probability and the spin polarization both periodically change with the increase of the well width.     

The effect of spin-orbit splitting on the valence band density of states of lead

Tight-binding calculations are reported for the valence bands of lead, with and without spin-orbit splitting in the 6p bands. The addition of spin-orbit interaction is necessary to reproduce the two-peaked structure in the 6p density of states observed in X-ray photoemission, in contrast to the assertion by Breeze that crystal-field effects alone are enough. The observed splitting is, however, only fortuitously nearly equal to the atomic spin-orbit splitting. The tight-binding band structure, with spin-orbit splitting, gives better overall agreement with optical, Fermi surface, and photoemission data than did any of the three earlier band structures.     

场频率变化时原子与场的相互作用

讨论了场频率随时间变化时二能级原子与相干态光场的相互作用. 分析了两种典型的情况，即场频率随时间作正弦变化以及作脉冲变化的情况. 研究发现：当场频率随时间作正弦变化时，原子布居数反转的崩塌和回复现象将消失；当场频率随时间作脉冲变化时,布居数反转随时间的演化将诱发出新的崩塌和回复过程. 关键词： Jaynes-Cummings模型 布居数反转 拉比振荡