The above SOC **signatures** can be possibly identified by the magneto-conductivity (MC) **transport** experiment[12]. The SOC in conventional 2D electron gas will turn the disorder class from weak-localization (WL) to weak anti-localization (WAL) by changing the quantum interference. However, the contribution of SOC in quantum conductivity is more complicated in **graphene** due to its unusual chirality [1, 38]. **Graphene** with smooth disorder is predicted to exhibit WAL [1]; However, strong inter-valley scattering, which typically arises in ordinary-quality samples, suppresses the chirality-related WAL and generates weak localization (WL) [24, 31]. While introducing strong Rashba SOC, the electron **spin** precesses around the effective magnetic field and acquires an additional π phase in the interference [25]—reviving WAL due to **spin**. Intrinsic (Kane-Mele) SOC terms, by contrast, break an effective time reversal symmetry and thus place the system in the unitary class (suppressed WL) [25]. Note that the SOC has to strong enough to participate in the interference before the electron dephasing out—i.e. the relaxation rate exceeds the inelastic de- phasing rate. Though intrinsic SOC is the most important SOC to realized quantum **spin** Hall phase, it is hard to pinpoint its existence by MC since unitary behav- ior can come from not only intrinsic SOC, but also other decoherence sources as well. Therefore, in this work, we investigate the MC **signatures** in l = p, d-orbital adatom doped **graphene**, We also proposed a scheme to hunt for the SOC **signatures** this case and derive the corresponding magneto-conductivity formula and **spin**- relaxation rates.

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Evidence for the LL behaviour of interacting 1D electrons has been reported for charge **transport** in SWNTs [2, 3, 4]. However, in such **materials** one also expects to find more dramatic consequences of the breakdown of Fermi liquid theory, most notably the phenomenon of **spin**-charge separation. This many-body effect asserts that electrons brought into a LL effectively break up into a charge and a **spin** part that travel with different velocities and hence will be spatially separated after some time. A recent proposal to detect evidence for **spin**-charge separation in SWNTs has been **based** on **spin** **transport** [8]. A different (and perhaps easier to realize) proposal **based** on electron **spin** resonance (ESR) is reviewed in this paper, expanding on our short paper [10]. ESR is a valuable experimental tool to probe the intrinsic **spin** dynamics of many systems. In ESR experiments one applies a static magnetic field and measures the absorption of radiation polarized perpendicular to the field direction. In the absence of SU(2) **spin** symmetry breaking terms in the Hamiltonian, the absorption intensity is then simply a δ-peak at the Zeeman energy [11, 12].

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X = Zr, Hf, and Y = S, Se, Te) and opens up the possibil- ity to observe this **coupling** in bilayers of these **materials** and **graphene**. Less attention has been paid to this family [55,56] compared to group-V and -VI TMDs. The application of Zr-**based** chalcogenides in solar-energy devices has been suggested [56], and the possibility of tuning its properties by pressure, electric field, and phase engineering was recently explored in density functional theory calculations [57]. Our findings suggest that TMDs of family IV are potential candi- dates to induce nontrivial **spin** textures in **graphene** via prox- imity **coupling**. On the other hand, the anisotropic Bychkov- Rashba **coupling** requires ǫ xz = ǫ yz , which is only possible in a

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Band inversion is a necessary condition for inducing TI phase. Applying strain is one of the methods to cause a band inversion. If **spin**-**orbit** **coupling** (SOC) is ignored, system usually becomes metallic due to the band cross- ing caused by the band inversion between the highest valence band (VBM) and the lowest conduction band (CBM). SOC is the key to opening a gap (SOC gap) at such crossing point to keep the systems remaining insulating in bulk and meet another necessary condition of inducing TI phase. Furthermore, if TI phase is induced, and the bulk band gap is large enough, such a TI phase continues to exist at room temperature and has a small finite size effect [33] and may become one of the promising candidates of spintronic devices.

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Photoemission spectroscopy is **based** on the photoelectric effect discovered by Hertz in 1887 [23]. In the 1880s Hertz was working on the generation and properties of electrical oscillations. His experiments proved the existence of electromagnetic waves, predicted by Maxwell, but also revealed a new phenomenon, the photoelectric effect. Hertz noticed that metal contacts exhibit enhanced ability to spark when exposed to light. Shortly after Hertz published his results, Hallwachs observed that negatively charged plates are loosing their charge when exposed to UV light while positively charged ones do not [24]. The interpretation of these findings was far from trivial as the electron was only discovered a decade after Hallwachs’ experiments. In 1899 J. J. Thomson [25] reported the discovery of new tiny sub-particles with negative charge, later called electrons. Following work of Hertz and Hallwachs in 1902 Lenard [26] performed a series of breakthrough experiments. He measured the energy distribution of photoelectrons by applying a variable retarding potential. From the results he concluded that the number of emitted electrons depends on the intensity of the light and, surprisingly, that their velocity depends only on the light frequency. On the basis of current knowledge at the time Lenard could not explain the relationship between the maximum kinetic energy of electrons and the wavelength of the incident radiation.

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Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, NL-2300 RA Leiden, The Netherlands (Received 5 August 2011; revised manuscript received 25 October 2011; published 9 November 2011) There exists a variety of proposals to transform a conventional s-wave superconductor into a topological superconductor, supporting Majorana fermion midgap states. A necessary ingredient of these proposals is strong **spin**-**orbit** **coupling**. Here we propose an alternative system consisting of a one-dimensional chain of magnetic nanoparticles on a superconducting substrate. No **spin**-**orbit** **coupling** in the superconductor is needed. We calculate the topological quantum number of a chain of finite length, including the competing effects of disorder in the orientation of the magnetic moments and in the hopping energies, to identify the transition into the topologically nontrivial state (with Majorana fermions at the end points of the chain).

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The energy-mapping method described above is objective in that, once a set of **spin** exchange paths is chosen for a magnetic solid, it does not presume whether the associated **spin** exchange parameters should be FM or AFM. This method simply maps the electronic energy spectrum of DFT+U calculations onto the energy spectrum of the **spin** Hamiltonian defined by a set of **spin** exchange parameters. However, the values of the resulting **spin** exchange parameters depend on what set of exchange paths one selects. In identifying the **spin** lattice appropriate for a magnetic solid under consideration, therefore, energy-mapping analysis should be carried out for a set of **spin** exchange paths large enough to include all important ones. In particular, for magnetic solids consisting of both M-O-M and M-O…O-M **spin** exchange paths, those M-O…O-M paths with short O…O contact distances should not be omitted in the energy-mapping analysis.

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The weak point here is connected with the na- ture of driving force for the **spin** flip in Eq. (2). Mas- sey made no comments about this. One can propose logically that Massey has taken into account the ideas of RPT [23] which were popular that time. The square brackets in Eq. (2) denote the solvent cage for radical pair which is really big and embraces a micro-part of solvent volume [23]. It means that two radicals can be far separated before their secondary collision and **spin** evolution proceeds during free dif- fusion of radicals inside solvent cage between two collisions. According to RPT the driving force for **spin** inversion in such radical pair is represented by very weak electron-nuclear **spin**-**spin** interac- tion (hyperfine **coupling**, 10 -4 cal/mol) inside each

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We present an open version of the symplectic kicked rotator as a stroboscopic model of electrical conduction through an open ballistic quantum dot with **spin**-**orbit** scattering. We demonstrate numerically and analytically that the model reproduces the universal weak localization and weak antilocalization peak in the magnetocon- ductance, as predicted by random-matrix theory 共 RMT 兲 . We also study the transition from weak localization to weak antilocalization with increasing strength of the **spin**-**orbit** scattering, and find agreement with RMT. DOI: 10.1103/PhysRevB.72.235305 PACS number 共 s 兲 : 73.63.Kv, 05.45.Pq, 71.70.Ej, 73.20.Fz

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In a short summary, we estimated the probability of transmission through the rectan- gular potential step and the barrier, if the electron-phonon scattering is included in the consideration. The correction to the ideal case (i.e., no EPC) was calculated in the ﬁrst order of the TDPT. We demonstrated that, by the most conservative estimates, the size of the device that takes advantage of the electron’s pseudospin degree of freedom in MLG, can be of the order of 10 µm, if EPC is the dominant scattering mechanism. Beyond this threshold, the tunneling probability at normal incidence can drop from unity to below 90%. At the same time, the calculations show that in case of such large devices the ﬁrst order of TDPT provides a limited accuracy as the electron becomes more likely to be scattered more than once. The indicator of the insuﬃciency of the ﬁrst order in the perturbation theory expansion is the norm deﬁned in Eq. (5.69): a substantial deviation of N from unity is the evidence a low accuracy of such approximation. However, our estimations of N show that the obtained tunneling probabilities provide a correct semi- quantitative picture even in the extreme cases of larger L and E k . This claim is **based** on

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In this paper we shall focus on the effects of Zeeman and exchange **spin** splitting and postpone the interesting problem of **spin**-**orbit** **coupling** to a future work. We show that the **spin**-resolved transmissions exhibit a strong de- pendence on the incidence angle, which allows in princi- ple for a selective transmission of **spin**-up and **spin**-down electrons. This effect can be qualitatively understood by a simple semiclassical argument. The bending of the elec- tron trajectories under the barrier depends on the energy and thus, in the presence of **spin** splitting, is different for the two **spin** projections. The magnitude of the polariza- tion that can be achieved depends on the **spin** splitting and can be very large in the presence of a large split- ting, as, e.g., that originating from a proximity-induced exchange field. Moreover, in a resonant double barrier configuration, the polarization can be enhanced by in- creasing the distance between the barriers. In this case, in fact, even for relatively small splitting there exists an energy range where the polarization reaches values close to one for large enough distance.

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Abstract. The role of the nuclear **spin**-**orbit** **coupling** on the equilibrium composition and on the equation of state of the outer crust of a nonaccreting neutron star is studied by employing a series of three different nuclear mass models **based** on the self-consistent Hartree-Fock-Bogoliubov method.

In order to investigate the eﬀect of the size of **graphene** ﬂakes on the magnetic orderings, we ﬁrst consider the three BNC structures under periodic boundary conditions for all directions. Figure 1 shows the computational mod- els employed here, where 64 atoms are included in the supercell and the number of boron atoms is larger than that of nitrogen atoms. The number of k point used in the two-dimensional Brillouin zone integration is 16. For all the calculations in this paper, a repeating sheet model is separated by 17.0 bohr in each layer. The lattice con- stant is 2.67 bohr, which is obtained by the bond length of the **graphene** sheet. Structural optimization is performed until the remaining forces are less than 0.08 eV/bohr. Table 1 shows the calculated magnetic moments of the BNC structures. The bottom panels of Figure 1 illustrate the diﬀerence between up-**spin** and down-**spin** charge- density distributions n ↑ (r) − n ↓ (r) of the BNC structures. The BNC sheet with the smallest **graphene** ﬂake is found to be the largest magnetic moment, and the **spin**-polarized charge-density distribution accumulates at the **graphene** ﬂake region.

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[69] Cuong, T. V., Pham, V. H., Chung, J. S., Shin, E. W., Yoo, D. H., Hahn, S. H. & Kohl, P. A. (2010). Solution-processed ZnO-chemically converted **graphene** gas sensor. **Materials** Letters, 64(22), 2479-2482. [70] Uddin, A. I., Phan, D. T., & Chung, G. S. (2015). Low temperature acetylene gas sensor **based** on Ag nanoparticles-loaded ZnO-reduced **graphene** oxide hybrid. Sensors and Actuators B: Chemical, 207, 362-369. [71] Sridevi, S., Vasu, K. S., Bhat, N., Asokan, S., & Sood, A. K. (2016). Ultra sensitive NO2 gas detection using the reduced **graphene** oxide coated etched fiber Bragg gratings. Sensors and Actuators B: Chemical, 223, 481-486. [72] Su, P. G., & Yang, L. Y. (2016). NH3 gas sensor **based** on Pd/SnO2/RGO ternary composite operated at room-temperature. Sensors and Actuators B: Chemical, 223, 202-208.

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We now consider two different SOI parameter sets consistent with the estimates in Ref. 12, and show the complete evolution of the Landau levels from the weak- to the strong-field limit. In Fig. 1, numerical results for the few lowest-energy Landau levels are depicted for ∆ > λ/2, corresponding to a QSH phase for B = 0. The (valley-degenerate) **spin**-split levels corresponding to the ∆ = λ = b = 0 zero mode exhibit a zero-energy crossing at B ≈ 11 T for the chosen SOI parameters. This crossing signals a quantum phase transition from the QSH phase, which survives for sufficiently small B and ∆ > λ/2, to a peculiar QH phase for large B. As we discuss in Sec. IV, one then again has helical edge states 20

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Generating pure spin current by applying electric field Present in non-magnetic semiconductors?. Mechanisms:.[r]

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Recent experiments in iron pnictide superconductors reveal that, as the putative magnetic quantum critical point is approached, different types of magnetic order coexist over a narrow region of the phase diagram. Although these magnetic configurations share the same wave vectors, they break distinct symmetries of the lattice. Importantly, the highest superconducting transition temperature takes place close to this proliferation of near-degenerate magnetic states. In this Letter, we employ a renormalization group calculation to show that such a behavior naturally arises due to the effects of **spin**-**orbit** **coupling** on the quantum magnetic fluctuations. Formally, the enhanced magnetic degeneracy near the quantum critical point is manifested as a stable Gaussian fixed point with a large basin of attraction. Implications of our findings to the superconductivity of the iron pnictides are also discussed.

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The standard method to extract SOI strength in extended regions is through low-field magnetoconductance (MC) mea- surements [21,22]. Quantum interference (see Fig. 1) in the presence of a strong SOI results in an increased conductance, called weak antilocalization (WAL) [23], that reduces to its classical value when a magnetic field is applied [24]. From fits of MC data to theory a **spin** relaxation length is extracted. If **spin** relaxation results from inversion asymmetry, a **spin** precession length and SOI strength can be defined. To extract SOI strength in nanowires the theory should contain (1) the length over which the electron dephases in the presence of a magnetic field, the magnetic dephasing length [25], and (2) the relation between **spin** relaxation and **spin** precession length [26]. The magnetic dephasing and **spin** relaxation length depend on, besides magnetic field and SOI strength, respectively, dimensionality and confinement. For instance, in nanowires, the **spin** relaxation length increases when the wire diameter is smaller than the **spin** precession length [26–28]. Therefore, the **spin** relaxation length extracted from WAL is not a direct measure of SOI strength. These effects have been studied in 2D wires [25,26], but results for 3D wires are lacking. As geometry and dimensionality are different (see Fig. 1), using 2D results for 3D wires is unreliable. Thus, a theory for 3D wires has to be developed.

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Abstract The present study investigated **spin** force by using pseudo **spin**-**orbit** **coupling** in an artificial atomic structure for **graphene**. This **spin** force, which is applied on pseudo **spin** current, can be controlled by **graphene** gap and electric field due to charged nanodot. It seems that, by this force can be constructed a logical system from **graphene** and semiconductors. In addition, this force can be used for understanding the Zitterbewegung of electron wave packet with pseudo **spin**-**orbit** **coupling** in **graphene** and create of the charge Hall effect in semiconductors and **graphene**.

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For the benefit of the focussed reader, we briefly sum- marize the main results of our analyis. The effective low- energy theory of an interacting Rashba quantum wire is given in Eq. (29), with the velocities (30) and the di- mensionless interaction parameters (31). Previous theo- ries did not fully account for the e-e backscattering pro- cesses, and the conspiracy of these processes with the broken SU (2) invariance due to **spin**-**orbit** effects leads to K s < 1 in Eq. (31). This in turn implies novel ef-

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