Spin-up States Research Articles

First principles study on the functionalization of graphene with Fe catalyst for the detection of CO2: Effect of catalyst clustering

The surface functionalization of graphene plays an important role in the development of graphene-based sensors for gas detection and removal. Here, we report the effect of decoration of graphene with Fe catalyst, as either scattered adatoms (Feadatoms@G) or clustered (Fecluster@G) on the detection of CO2 gas molecule and its influence on the structural, adsorption, electronic and magnetic properties of graphene using the spin-polarized density functional theory (DFT). The results show that the adsorption of scattered Fe-adatoms and Fe4-cluster on graphene would break the degeneracy of spin-up and spin-down states, resulting in ferromagnetic adsorption-bed for the detection of CO2 molecules. The magnetic moment of Feadatoms@G remains the same for all concentration of CO2, while the magnetic moment of Fecluster@G decreases from 10.03 µB to 4 µB by increasing the concentration of CO2 from one to four molecules. It is found that the scattered Fe-adatoms on graphene have the higher tendency to adsorb more CO2 molecules than that of the cluster with the same number of Fe atoms, whereas Fe4-cluster on graphene detects CO2 molecules using magnetism. Our results have indeed a direct application to fabricate solid-state and magnetic-based gas sensors using graphene to detect CO2 gas molecules.

Two dimensional ferromagnetic semiconductor: monolayer CrGeS3

Recently, two-dimensional ferromagnetic semiconductors have been an important class of materials for many potential applications in spintronic devices. Based on density functional theory, we systematically explore the magnetic and electronic properties of CrGeS3 with the monolayer structures. It is found that the bandgap of spin-up state is 1.01 eV when it is 1.07 eV in spin-down state. The exchange splitting is calculated as 0.67 eV (2.21 eV by HSE06 functional), which originates from bonding hybridized states of Cr eg-S p and unoccupied Cr t2g-Ge p hybridization. After that, the comparison of total energy between different magnetic states ensures the ferromagnetic ground state of monolayer CrGeS3. The reason of the magnetic states originates mainly from the competition between antiferromagnetic direct neighboring Cr–Cr exchange and ferromagnetic superexchange mediated by S atom. And the results also show the magnetic moment of 6 per unit cell, including two Cr atoms. Besides, we estimate that the monolayer CrGeS3 possesses the Curie temperature of 161 K by mean-field theory. The results suggest that monolayer CrGeS3 crystals will possess potential applications in nanoscale spintronics.

Tuning spin state of Ru4+ ion and Jahn-Teller distortion in cubic SrRuO3 system by controlling in-plane strain: A first-principle study

We report the electronic and magnetic properties of the ferromagnetic metallic SrRuO3 system using the plane-wave method within the GGA. The initial evaluation of the effect of effective Hubbard energy (Ueff = U − J) on crystal structure reveals the fully-optimized lattice parameters of a = 4.0496 and 4.0615 Å for Ueff = 0 and 2.9 eV, respectively. Then, we control the in-plane strain (εxx) in the range of εxx = −0.2 to −2.0% within the GGA + U. For all εxx values, the metallic behavior comes from the spin-up Ru 4d-eg and spin-down Ru 4d-t2g states overlapping the Fermi energy level. We find that the increment of the absolute value of εxx (|εxx|) enhances the local magnetic moment of Ru4+ ion, which exhibits the mixed low-spin and high-spin states. Interestingly, the increment of |εxx| enhances the Jahn-Teller distortion, the high-spin state contribution, and the exchange splitting between spin-up and spin-down states in Ru4+ 4d orbital. Additionally, the increment of |εxx| also increases and decreases the local magnetic moments of xy-plane and z-axis O2- ions, respectively. Our result highlights the significant role of εxx in tuning the spin state and Jahn-Teller distortion of Ru4+ ion in the system, which is essential for novel magnetic device applications.

Rationally Designed High-Performance Spin Filter Based on Two-Dimensional Half-Metal Cr2NO2

Summary Half-metals are promising candidates for designing efficient spin filters owing to their unique electronic structures, which show the electrical conductivity for spin-up states and a band gap for spin-down states. Herein, designing excellent ultrathin spin filters by using half-metal two-dimensional Cr2NO2, which has a Curie temperature of 566 K, is demonstrated based on first-principles calculations. Our results reveal that the required energy to overturn the spin arrangement of bilayer Cr2NO2, from parallel to anti-parallel states, is quite low. The bilayer Cr2NO2 maintains its half-metal behavior while sandwiched within the Au/Cr2NO2/Au heterojunction. Owing to the half-metal characteristic, the total current of Au/Cr2NO2/Au can reach a value of 15 nA per primitive cell under a low voltage of 10 mV in parallel states. The magnetoresistance ratio is 9,333% at low voltage. The robust half-metal behavior, high Curie temperature, and two-dimensional structure make Cr2NO2 an ideal ultrathin spin-filtering material with high switching ratio and low energy consumption.

Magnetic, Electronic, Mechanic, Anisotropic Elastic and Vibrational Properties of Antiferromagnetic Ru2TGa (T = Cr, Mn, and Co) Heusler Alloys

A theoretical study of magnetic, electronic, mechanic, anisotropic elastic, and vibrational properties of $$ {\hbox{Ru}}_{2} $$ TGa (T = Cr, Mn, and Co) Heusler alloys has been extensively investigated by the first-principles method using the generalized gradient approximation. Structural parameters such as lattice constant ( $$ a_{0} $$ ), bulk modulus (B) and first pressure derivative of bulk modulus (B′) were obtained by using the Murnaghan equation. The calculated formation enthalpies ( $$ \Delta H_{f} $$ ) showed that these alloys are thermodynamically stable. The total spin magnetic moments per unit cell of $$ {\hbox{Ru}}_{2} $$ TGa (T = Cr, Mn, and Co) alloys were found to be 1.16 $$ \mu_{B} $$ , 2.16 $$ \mu_{B} $$ and 0.29 $$ \mu_{B} $$ , respectively. In addition to electronic band structures along the high symmetry directions, corresponding total and partial density of states were also plotted. It was found that the spin-up states have a metallic character for all alloys, but the spin-down states of the other alloys except for $$ {\hbox{Ru}}_{2} $$ CoGa have a pseudo-gap at the Fermi level. The bulk modulus (B), shear modulus ( $$ G $$ ), ratio of B/ $$ G $$ , Young’s modulus (E), Poisson’s ratios (ν), Vickers hardness ( $$ H_{V} $$ ), sound velocities ( $$ v_{l} $$ , $$ v_{t} $$ , and $$ v_{m} $$ ), Debye temperatures ( $$ \varTheta_{D} $$ ) and melting temperatures ( $$ T_{\rm{melt}} $$ ) were obtained from elastic constants ( $$ C_{ij} $$ ) in accordance with the Voigt–Reuss–Hill approximation. The calculated elastic constants showed that these alloys are mechanically stable and they have anisotropic character. The elastic anisotropy of the considered alloys was analyzed and pictured in great detail with 2D and 3D figures of directional dependence of Young’s modulus, linear compressibility, shear modulus, and Poisson’s ratio.These alloys are dynamically stable because there are no negative modes in their phonon dispersion curves.

Spectral and Timing Analysis of the Accretion-powered Pulsar 4U 1626–67 Observed with Suzaku and NuSTAR

Abstract We present an analysis of the spectral shape and pulse profile of the accretion-powered pulsar 4U 1626−67 observed with Suzaku and Nuclear Spectroscopic Telescope Array (NuSTAR) during a spin-up state. The pulsar, which experienced a torque reversal to spin-up in 2008, has a spin period of ∼7.7 s. Comparing the phase-averaged spectra obtained with Suzaku in 2010 and with NuSTAR in 2015, we find that the spectral shape changed between the two observations: the 3–10 keV flux increased by ∼5%, while the 30–60 keV flux decreased significantly by ∼35%. Phase-averaged and phase-resolved spectral analysis shows that the continuum spectrum observed by NuSTAR is well described by an empirical negative and positive power law times exponential continuum with an added broad Gaussian emission component around the spectral peak at ∼20 keV. Taken together with the observed value obtained from the Fermi/gamma-ray burst monitor data, we conclude that the spectral change between the Suzaku and NuSTAR observations was likely caused by an increase in the accretion rate. We also report the possible detection of asymmetry in the profile of the fundamental cyclotron line. Furthermore, we present a study of the energy-resolved pulse profiles using a new relativistic ray tracing code, where we perform a simultaneous fit to the pulse profiles assuming a two-column geometry with a mixed pencil- and fan-beam emission pattern. The resulting pulse profile decompositions enable us to obtain geometrical parameters of accretion columns (inclination, azimuthal and polar angles) and a fiducial set of beam patterns. This information is important to validate the theoretical predictions from radiation transfer in a strong magnetic field.

Ab initio study of (FeCpVCp)n@MoS2 NT — A one-dimensional bimetallic sandwich molecular wire (FeCpVCp)n encapsulated into MoS2 nanotube

We present a theoretical study on a novel one-dimensional nanomaterial (FeCpVCp)n@MoS2 NT which are constructed with encapsulating organometallic sandwich molecular wires (FeCpVCp)n into armchair (8, 8) MoS2 NT, using density functional theory (DFT) and nonequilibrium Green’s function (NEGF) techniques. It is found that ferromagnetic (FeCpVCp)n@MoS2 NT is thermally stable with a high Curie or Neél temperature of 722.8 K. Transport property of (FeCpVCp)n@MoS2 NT is in good agreement with the electronic structure. (FeCpVCp)n offers a notable transport pathway along the axial direction, electron hopping may happen from (FeCpVCp)n to MoS2 NT sheath, which plays a significant role in electron transporting. Conductivity of (FeCpVCp)n@MoS2 NT is dependent on the spin states: spin-down state gives a higher conductivity than the spin-up state, opening out a spin-polarized transport property. These novel properties of (FeCpVCp)n@MoS2 NT render their potential applications in nanoscale spintronic and molecular electronics.

(Bz)n and (VBz)n covalent functionalized MoS2 monolayer: electronic and transport properties

Inspired by Benzene (Bz) derivatives dramatically enhancing MoS2 monolayer electronic properties (ACS Nano. 2015, 9, 6018–6030), we have investigated electronic and transport properties of (Bz)n/MoS2 and (VBz)n/MoS2, which are designed by grafting (Bz)n and (VBz)n arrays onto 2D monolayer MoS2 (ML-MoS2), respectively, using density functional theory (DFT) and non-equilibrium Green’s function (NEGF) methods. ML-MoS2 provides a perfect substrate for grafting (Bz)n and (VBz)n arrays upon its surface as a result of stable covalent binding energy with −3.841 eV and −1.953 eV for (Bz)n/MoS2 and (VBz)n/MoS2 respectively. From the electronic properties, we can find that grafting (Bz)n onto the ML-MoS2 surface turns ML-MoS2 from typical semiconductor to metallic properties because four wide bands coupled by (Bz)n and MoS2 in (Bz)n/MoS2 show better delocalization in heterointerface, resulting to these bands across the Fermi level (Ef). Furthermore, (VBz)n nanowire grafted on the ML-MoS2 further enhances the conductivities due to the introduction of metal V. Transport properties of ML-MoS2, (Bz)n/MoS2 or (VBz)n/MoS2 for two-probe devices are all studied in zigzag and armchair direction. By comparison the zigzag direction is the preferential pathway for electron transport. The ferromagnetic (VBz)n/MoS2 shows a spin polarized transport characteristic, spin-down state gives a higher conductivity than spin-up state. Finally this work suggests that the novel (VBz)n nanowire grafted on MoS2 should have potential application in low-dimensional magnetic nanoelectronic devices.

First-principles study of electronic structure, magnetic and optical properties of laminated molybdenum oxides

According to the pseudopotential plane-wave method of first-principles calculation based on the spin density functional theory, the electronic structure, magnetic and optical properties of laminated molybdenum oxides (orthonormal and monoclinic MoO<sub>3</sub>) are studied theoretically. The interlaminar dissociation energy, band-structure, spin polarization, dielectric function, and the optical absorption/reflectivity in a charged state are systematically calculated to explore the potential technology applications of laminated MoO<sub>3</sub> as electrochromic or electromagnetic materials in optoelectronic devices. The semilocal GGA-PW91 and nonlocal HSE06 exchange-correlation functional are employed to obtain the more accurate crystal structure and band gap respectively. The cleavage energy results indicate that the single layers can easily flake off from the bulk material of these molybdenum oxides. The band structure and atomic-projected density of states prove that the conduction band minimum and valence band maximum are mainly derived from the atom-orbitals bonding oriented in layer-plane, representing characteristic two-dimensional electronic structure. The spin polarized calculations imply that the evident magnetic-moment will engender in MoO<sub>6</sub> octahedron layers of the perfect MoO<sub>3</sub> due to the substantial spin polarization of Mo and vertex O atoms which are ferromagnetic-coupling to produce significant net magnetic moments, essentially accounting for the magnetic source of bulk MoO<sub>3</sub>. The Mo vacancy reduces the electronic density of states derived from the spin polarized d-orbitals, leading the net magnetic moment to decrease, while the O<sub>I</sub> vacancy can reduce the density of spin-down states in the MoO<sub>3</sub>, resulting in the significant improvement of net magnetic moment. The existence of O<sub>II</sub> vacancy leads to the energetic spin-splitting of O-2p and Mo-4d orbital states, and thus increasing net magnetic moment by raising the electronic density of polarized spin-up states. The electron spin polarization of Mo-4d orbital component dominantly contributes to the bulk magnetism. The laminated MoO<sub>3</sub> presents a significant optical response in the visible region with obvious anisotropy of optical absorption spectra, which will represent a considerable blue shift or new low-frequency absorption peaks for visible light when loading charges. The calculation results demonstrate that the laminated molybdenum oxides have evident electrochromic property with controllable magnetic moment, which provides theoretical basis and technical data for developing novel functional materials with high performance to be used in electromagnetic or optoelectronic devices.

A complete DFT description on structural, electronic, elastic, mechanical and thermodynamic properties of some intermetallic AuX2 (X = Al, Ga, In) compounds

The electronic structure, elastic, mechanical and thermodynamic properties of some cubic intermetallic compounds AuX2(X = Al, Ga, In) have been studied within the density functional theory (DFT) using the full potential linearized augmented plane-wave technique (FP-LAPW). The designed values of structural parameters including lattice constant, bulks modulus and ground-states energies are found in good agreement with the available data. The spin included electronic examination presents the metallic nature for all the three compounds with symmetry in spin-up and spin-down states. The elastic properties have been calculated under ambient conditions and have been used to envisage some vital mechanical factors like bulk modulus (B), Young’s modulus (Y), shear modulus (G), Poisson ratio ( $ \nu$ ) and anisotropic factor (A). The calculated results reveal that AuX2(X = Al, Ga, In) compounds establish low elastic anisotropy, low hardness and high ductility. Quasi-harmonic Debye approximation has been used to investigate pressure and temperature dependence of bulk modulus (B), heat capacity (Cv), thermal expansion ( $ \alpha$ , and Debye temperature ( $ \theta_{\rm D}$ . Furthermore, Cv was found to strictly follow the Debye T3-law and Dulong-Petit limit for all the three compounds.

Spin orbit coupling induced band gap in gemanene modulated by external field

We investigate the electronic band structure of germanene crystal by using the sixteen band tight-binding calculation. We focus on the modulation of its band gap with spin–orbit coupling (SOC), perpendicular electric field and magnetic field. Our calculation shows that the SOC opens a tunable band gap in the Dirac-type electronic structures, and plays a crucial rule in the formation of the energy band gap. The influence of SOC on the gap in germanene is much larger than that in graphene, which makes germanene an ideal candidate to exhibit the quantum spin Hall effect at room temperature. We also find that the electronic structure and topological property of germanene can be tuned by the external field significantly. Thus the electronic structure of germanene can be controlled to produce metallic, semiconducting, or insulating properties by applying an appropriate external field. In addition, the key features of the band structure induced by the electrical field and magnetic field are quite different. For the electric field applied, two spin-up states produce a gap at K point, in contrast, two spin-down states do it at K′ points. While for the magnetic field present, the band gaps are formed by the spin-up states from the conduction band and spin-down state from the valance band at both the K and K′ points. This modulation behavior of the band gap by the external field paves a way to the realization of germanene based spintronic devices.

Ultrafast mixing of radial and spin states driven by transient magnetic field in concentric double quantum ring in presence of Dresselhaus spin-orbit interaction

We consider the single- and two-electron systems confined in concentric double quantum ring (DQR) nanostructure which interacts with transient perpendicular magnetic field oscillating with THz frequency. For this purpose we find the solutions of time-dependent Schrödinger equation utilizing Configuration Interaction method. We found that the transient magnetic field mixes the radial states, what trigger off the charge density oscillations in this direction, and these may be accompanied by spin oscillations, provided that a spin-orbit interaction (SOI) is involved. The pattern of density oscillations is more regular than those obtained for single- and two-electron spins what results from less complicated excitation energy spectra if SOI is not present in the system. The latter can be made more regular, i.e. the fluctuations of frequency and amplitude of spin oscillations shall be smaller, provided that the sign of the magnetic field at the beginning of time evolution is chosen appropriately since not all energy levels corresponding to Jˆz−=Lˆz−Sˆz eigenstates have mirror symmetry in relation to B → −B transformation. Our outcomes indicate, that the combined effect of a few-picosecond-long magnetic pulse and SOI on electron spin in DQR would enable one to perform transition between spin-up and spin-down states within 2 ps.

Magneto-Electronic, Thermodynamic, and Thermoelectric Properties of 5f-Electron System BaBkO3

In the present work, the structural, electronic, magnetic, mechanical, thermodynamic, and thermoelectric properties of cubic perovskite BaBkO3 were investigated within the framework of density functional theory using generalized gradient approximation, onsite Coulomb interaction, and modified Becke-Johnson methods. BaBkO3 is stable in the ferromagnetic phase with a magnetic moment of 7 μB. The spin-polarized electronic band structure reveals 100% spin polarization of the material with metallic character in spin-up state and semiconducting in spin-down state. Pugh and Cauchy relation displays that the material is highly ductile. The quasi-harmonic Debye model was used to determine the thermodynamic properties of BaBkO3 under high pressure and temperature. BaBkO3 presents high value of Seebeck coefficient and power factor at room temperature with a value of 135 μVK− 1 and 1.5 × 1012μWcm− 1 K− 2 s− 1, respectively. The possession of half metallicity and high Seebeck coefficient makes BaBkO3 suitable for spintronic and thermoelectric device applications.

Controlling the conductance of single-molecule junctions with high spin filtering efficiency by intramolecular proton transfer

Abstract The pursuit of miniaturization of magnetic electronic components spurs intensive theoretical and experimental researches on designing molecule-scale magnetic devices. Controlling the transport properties is one of the most vital focuses for magnetic molecular devices. In this work, magnetic devices constructed by a single epindolidione (Epi) molecule (5,11-dihydrodibenzo[b,g][1,5]naphthyridine-6,12-dione) bridging two zigzag graphene nanoribbon (zGNR) electrodes are theoretically designed. The Epi molecule can be converted between the keto and enol forms, which is confirmed by first principle molecular dynamics method. The influences of intramolecular proton transfer and the bridging manner between the core molecule and zGNR electrodes on the magnetic transport properties are investigated. Spin-resolved current-voltage (I-V) curves show that both the keto and enol devices display remarkable spin filtering effect. However, the effect of intramolecular proton transfer on the electron transport properties depends on the bridging manner between the Epi molecule and zGNR electrodes. When the Epi molecule is connected to zGNR electrodes with 4,7-sites (A bridging manner), the electron transport properties of molecular junctions are hardly affected by the intramolecular proton transfer. On the contrary, the conductance of the molecular junctions is significantly modulated by the intramolecular proton transfer when the Epi molecule is connected to zGNR electrodes with 4,4′-sites (B bridging manner). Further analysis reveals that the high spin filtering effect originates from stronger coupling between spin-up edge electronic states of zGNR electrodes and states of the core molecule. With B bridging manner, the conjugation characteristics of the Epi molecule as well as the transmission pathway of tunneling electrons can be largely modulated by the intramolecular proton transfer. Our work proposes a feasible way to control the conductance of single-molecule junctions by taking advantage of intramolecular proton transfer.

The kHz QPOs as a probe of the X-ray color–color diagram and accretion-disk structure for the atoll source 4U 1728-34

We have taken the kHz QPOs as a tool to probe the correlation between the tracks of X-ray color–color diagram (CCD) and magnetosphere-disk positions for the atoll source 4U 1728-34, based on the assumptions that the upper kHz QPO is ascribed to the Keplerian orbital motion and the neutron star (NS) magnetosphere is defined by the dipole magnetic field. We find that from the island to the banana state, the inner accretion disk gradually approaches the NS surface with the radius decreasing fromr∼ 33.0 km to ∼15.9 km, corresponding to the magnetic field fromB(r) ∼ 4.8 × 106G to ∼4.3 × 107G. In addition, we note the characteristics of some particular radii of magnetosphere-diskrare: firstly, the whole atoll shape of the CCD links the disk radius range of ∼15.9–33.0 km, which is just located inside the corotation radius of 4U 1728-34rco(∼34.4 km), implying that the CCD shape is involved in the NS spin-up state. Secondly, the island and banana states of CCD correspond to the two particular boundaries: (I)near the corotation radius atr∼ 27.2–33.0 km, where the source lies in the island state; (II)near the NS surface atr∼ 15.9–22.3 km, where the source lies in both the island and banana states. Thirdly, the vertex of the atoll shape in CCD, where the radiation transition from the hard to soft photons occurs, is found to be near the NS surface atr∼ 16.4 km. The above results suggest that both the magnetic field and accretion environment are related to the CCD structure of atoll track, where the corotation radius and NS hard surface play the significant roles in the radiation distribution of atoll source.

First-principle calculations of electronic and optical properties of CdCr2Te4 spinel: use of mBJ + U potential in narrow band gap semiconductors

In this study, we report the theoretical investigation of electronic structure and frequency-dependent optical properties of narrow band gap CdCr2Te4 normal spinel. While GGA + U and TB-mBJ schemes fail to show the semiconducting nature of CdCr2Te4 spinel, combining the mBJ potential with the Hubbard U correction obtains a narrow band gap of 0.04 eV. The indirect band gap using mBJ + U scheme occurs due to the shifting of spin-up Cr-eg and Cr-t2g states of conduction band towards higher energy. This reflects the better suitability of mBJ + U scheme to study the band structure of CdCr2Te4 as compared to the GGA + U, TB-mBJ, and expensive hybrid functional methods. The asymmetrical nature of spin-up and spin-down states in total DOS indicates them to be magnetic compounds. The integer value of total magnetic moment per formula unit rules out the metallic nature of this compound. We studied the optical spectra in terms of the band to band transitions for their possible use in optoelectronic applications.

A full potential all-electron calculation on electronic structure of NiO

We perform a first principle calculation on NiO system, a prototypical correlated electronic system due to partial filled 3d electronic shell, using various density functional theory (DFT) and hybrid functional methods inclusion of spin polarization (SP), on-site Coulomb repulsion U and spin–orbit coupling (SOC) effects. It is shown that localized spin density approximation (LSDA) plus U (LSDA + U) correctly reproduce experimental lattice parameter, while spin polarization generalized gradient approximation (SP + GGA + U) obviously overestimates lattice parameter. LSDA + U/SP + GGA + U band gaps and magnetic moments are in agreement with experimental data, and correctly predict NiO to be an insulator. NiO undergoes a Mott–Hubbard metal–insulator transition (MIT) by addition of Coulomb interaction U. Our LSDA + SOC calculation shows that SOC further splitting of Ni d eg and t2g orbitals into dz2, dxy, dx2y2 and dxz + dyz orbitals, and SP nearly cancels out SOC effect, giving rise to symmetry of density of states (DOS) for spin-up and spin-down states, hence appearance of zero net magnetic moment. For LSDA + U + SOC calculation, combination effect of SP, U and SOC results in non-occupying of spin-up conduction band and a negligible density of states for spin-down states.

Plasmon-phonon coupling in a valley-spin-polarized two-dimensional electron system: A theoretical study on monolayer silicene

We study the hybrid excitations due to the coupling between surface optical phonons of a polar insulator substrate and plasmons in the valley-spin-polarized metal phase of silicene under an exchange field. We perform the calculations within the generalized random-phase approximation where the plasmon-phonon coupling is taken into account by the long-range Fr$\ddot{\mathrm{o}}$hlich interaction. Our investigation on two hybridized plasmon branches in different spin and valley subbands shows distinct behavior compared to the uncoupled case. Interestingly, in one valley, it is found that while the high energy hybrid branch is totally damped in the spin-up state, it can be well-defined in the the spin-down state. Moreover, we show that the electron-phonon coupling is stronger in both spin-down subbands, regardless of valley index, due to their higher electron densities. In addition, we study the effects of electron-phonon coupling on the quasiparticle scattering rate of four distinct spin-valley locked subbands. The results of our calculations predict a general enhancement in the scattering rate for all subbands, and a jump in the case of spin-down states. This sharp increase associated to the damping of hybrid plasmon modes is almost absent in the uncoupled case. The results suggest an effective way for manipulating collective modes of valley-spin-polarized silicene which may become useful in future valleytronic and spintronic applications.

Electronic properties of pentagonal CN2 nanoribbon under external electric field and tensile strain

Cutting two-dimensional (2D) CN2 sheet along specific crystallographic orientations to construct CN2 nanoribbon, its electronic structure is investigated systemically. We show by first-principles calculations that the electronic properties of CN2 nanoribbon exhibit response to applied electric field and strain. The lowest conduction band and highest valence bands of the spin-up and spin-down states approach to the Fermi level respectively with increasing the strength of the electric field and tensile strain. More interestingly, an applied electric field can transform the nature of the CN2 nanoribbon from semiconductor to metal. These results provides us an efficient way to design spintronic devices based on the CN2 nanoribbons.

Photoemission process — Relation with quantum entanglement

It is well known that an electron has either spin-up or spin-down state and a photon has two possible polarizations called spin [Formula: see text] or spin [Formula: see text]. But when two particles are created, the two particles can have 50% of one state and 50% in the other. This is called the two particles in quantum entanglement. The spooky thing is that an event at one point in the universe can instantaneously affect the event that is arbitrarily far away between these two particles. a The entanglement of the two particles can be electron or photon. We believe, in order to study this phenomenon we have to study further than the previously established principles of quantum mechanics, that is, to study how an electron creates a photon and how it interacts with the photon emitted. a Quantum entanglement simplified-video results — Quantum entanglement and spooky action at a distance, youtube.com, two years ago.