ELECTRONIC PROPERTIES OF A HYDROGENIC IMPURITY IN A QUANTUM WIRE WITH V-SHAPED CROSS-SECTION: SPIN-ORBIT COUPLING, RELATIVISTIC CORRECTION AND CONDUCTANCE

2013 ◽  
Vol 24 (07) ◽  
pp. 1350041 ◽  
Author(s):  
R. KHORDAD ◽  
H. BAHRAMIYAN
Keyword(s):  
Cross Section ◽  
Quantum Wire ◽  
Energy Levels ◽  
Relativistic Correction ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Hydrogenic Impurity ◽  
Mass Approximation ◽  
Shaped Cross Section

The effects of spin-orbit coupling (SOC) and relativistic correction (RC) on the energy levels of a hydrogenic impurity in a GaAs/Ga 1-x Al x As quantum wire are studied. The quantum wire has a V-shaped cross-section and the impurity located in its center. Our numerical calculations have done using a variational procedure within the effective mass approximation. Our results show that (i) the splitting due to the SOC decreases with increasing the wire width, (ii) the SOC and RC increase when the concentration increases, (iii) the SOC is zero for l = 0 (l is angular momentum) and nonzero for l ≠ 0, (iv) for a given wire width, the RC is different for l = 0 and l = 1 due to expectation values of [Formula: see text] and [Formula: see text] (r is distance between the electron and impurity). We also computed the conductance of the quantum wire with and without impurity.

Ground configuration splitting in UCl5

1977 ◽  
Vol 55 (10) ◽  
pp. 937-942 ◽  
Author(s):  
A. F. Leung ◽  
Ying-Ming Poon
Keyword(s):  
Crystal Field ◽  
Energy Levels ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Coupling Constant ◽  
Point Charge Model ◽  
X Ray Crystallography ◽  
Charge Model ◽  
Crystal Field Parameters

The absorption spectra of UCl5 single crystal were observed in the region between 0.6 and 2.4 μm at room, 77, and 4.2 K temperatures. Five pure electronic transitions were assigned at 11 665, 9772, 8950, 6643, and 4300 cm−1. The energy levels associated with these transitions were identified as the splittings of the 5f1 ground configuration under the influence of the spin–orbit coupling and a crystal field of C2v symmetry. The number of crystal field parameters was reduced by assuming the point-charge model where the positions of the ions were determined by X-ray crystallography. Then, the crystal field parameters and the spin–orbit coupling constant were calculated to be [Formula: see text],[Formula: see text], [Formula: see text], and ξ = 1760 cm−1. The vibronic analysis showed that the 90, 200, and 320 cm−1 modes were similar to the T2u(v6), T1u(v4), and T1u(v3) of an UCl6− octahedron, respectively.

Persistent Spin Current in a Quantum Wire with Weak Rashba Spin–Orbit Coupling

2006 ◽  
Vol 23 (11) ◽  
pp. 3065-3068 ◽  
Author(s):  
Wang Yi ◽  
Sheng Wei ◽  
Zhou Guang-Hui
Keyword(s):  
Quantum Wire ◽  
Spin Current ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Rashba Spin

SPIN CURRENT INDUCED ELECTRIC FIELD IN A RASHBA QUANTUM WIRE

2010 ◽  
Vol 24 (07) ◽  
pp. 649-656
Author(s):  
XI FU ◽  
GUANGHUI ZHOU
Keyword(s):  
Electric Field ◽  
Current Density ◽  
Quantum Wire ◽  
Spin Current ◽  
Scattering Matrix ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Rashba Spin

We investigate theoretically the spin current and spin current induced electric field in a weak Rashba spin-orbit coupling quantum wire (QW) using a definition for spin current by means of scattering matrix. It is found that there exists two non-zero linear spin current density elements which have oscillation peaks at the center of QW and their strengths can be changed by the number of propagation modes and Rashba constant, respectively. Moreover, the spin current induced electric field has also been calculated and its strength is measurable with present technology with which can be used to detect spin current.

SPIN TRANSPORT FOR A QUANTUM WIRE WITH WEAK DRESSELHAUS SPIN-ORBIT COUPLING

2011 ◽  
Vol 25 (07) ◽  
pp. 487-496
Author(s):  
XI FU ◽  
ZESHUN CHEN ◽  
FENG ZHONG ◽  
YONGHONG KONG
Keyword(s):  
Spin Polarization ◽  
Quantum Wire ◽  
Spin Transport ◽  
Scattering Matrix ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Wall Potential ◽  
Electron Transport Properties ◽  
Scattering Matrix Method

We investigate theoretically the electron transport properties of a quantum wire (QW) non-adiabatically connected to two normal leads with weak Dresselhaus spin-orbit coupling (DSOC). Using the scattering matrix method and Landauer–Büttiker formula within the effective free-electron approximation, we have calculated the spin-dependent conductances G↑/↓ and spin polarization Pz of a hard-wall potential confined QW. It is demonstrated that regardless of the existence of DSOC G↑/↓ and Pz present oscillation structures near the subband edges of QW, and the number of quantized conductance plateaus is determined by the number of propagation modes in two leads. Moreover, the DSOC induces splitting of spin-up and spin-down conductance plateaus as well as the existence of spin polarization (Pz ≠ 0), and the enhancement of Dresselhaus strength destroys the conductance plateaus for the wide QW case. The above results indicate that the spin-dependent conductances and Pz are strongly dependent on the Dresselhaus strength which is the physical basis for spin transistor.

scholarly journals Electronic and magnetic properties of two dimensional crystals

2021 ◽  
Author(s):  
◽  
Hani Hatami
Keyword(s):  
Magnetic Properties ◽  
Transport Properties ◽  
Energy Levels ◽  
Bilayer Graphene ◽  
Orbit Coupling ◽  
Monolayer Graphene ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Two Dimensional ◽  
Electronic And Magnetic Properties

<p>In the last few years, two dimensional crystals have become available for experimental studies. Good examples of such systems are monolayers and bilayers of graphene and monolayers of transition metal dichalcogenides such as MoS₂ and WSe₂. The availability of two dimensional crystals has encouraged physicists to study the electronic and magnetic properties of such systems. This thesis adds to the theoretical knowledge about electronic and magnetic properties of two dimensional crystals with the focus on graphene and MoS₂.  As a general theme in this thesis, we calculate how in general these systems interact with electric and magnetic fields and what their response is to such stimuli. In particular, we have studied the response of monolayer graphene to an in-plane electric field. We have also looked at spin-orbit coupling effects that arise from applying perpendicular or in-plane external electric fields, especially their consequences for transport properties of bilayer graphene. We investigated the electronic properties of charge carriers confined in a mesoscopic ring structure using a gate voltage in bilayer graphene. We also showed how spin-orbit coupling can affect the electrical properties of such rings. We found how spin-orbit coupling can affect the transport properties in bilayer graphene. We also investigated the RKKY or indirect exchange coupling between magnetic moments in monolayer MoS₂ through calculating wave vector dependent spin susceptibility.  We examined the electronic properties of electrons and holes confined electrostatically into a bilayer graphene ring. We presented an analytical solution for finding energy levels in the ring. We showed that the magnetic field dependence of the lowest energy level with fixed angular momentum in bilayer graphene rings, in contrast to usual semiconductor quantum rings, is not parabolic but displays an asymmetric “Mexican hat“. We found that introducing spin-orbit coupling in the ring can flatten this Mexican hat.  We studied the effect of an orbital Rashba type effect, induced by an in-plane electric field in monolayer graphene. Using perturbation theory, we showed that this term can affect the energy levels in a crossed electric and magnetic field such that the electron and hole levels repel each other. We calculated the AC transport of monolayer graphene in the linear-response regime and showed that taking the orbital Rashba term into account casts doubt on the universality of the minimum conductivity of monolayer graphene.  We studied the effect of spin-orbit coupling in transport properties of bilayer graphene systems by calculating tunnelling through npn and np junctions. We showed that at sufficiently large spin-orbit strength, normal transmission through a barrier which is forbidden in bilayer graphene becomes finite. We predict that in a weak Rashba spin-orbit regime, outgoing electrons show signals which are spin polarized. We also showed that considering spin-orbit coupling only in the barrier of an npn junction can invert the spin of the incoming electrons.  Finally, we obtained analytical expressions for the wave vector-dependent static spin susceptibility of monolayer transition metal dichalcogenides, considering both the electron-doped and hole-doped cases. These results are then applied to the calculations of physical observables of monolayer MoS₂. We claculated that the hole-mediated RKKY exchange interaction for in-plane impurity-spin components decays with a different power law from what is expected for a two-dimensional Fermi liquid. In contrast, we calculated that the out-of-plane spin response shows the conventional long-range behaviour.</p>

scholarly journals Electronic states and persistent currents in nanowire quantum ring

2018 ◽  
Vol 52 (4) ◽  
pp. 486
Author(s):  
I.A. Kokurin
Keyword(s):  
Magnetic Field ◽  
Energy Levels ◽  
Persistent Current ◽  
Orbit Coupling ◽  
Quantum Ring ◽  
Pure Spin ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Persistent Currents ◽  
The One

AbstractA new model of a quantum ring defined inside a nanowire is proposed. The one-particle Hamiltonian for electron in [111]-oriented nanowire quantum ring is constructed taking into account both Rashba and Dresselhaus spin-orbit coupling. The energy levels as a function of magnetic field are found using the exact numerical diagonalization. The persistent currents (both charge and spin) are calculated. The specificity of spin-orbit coupling and arising anticrossings in energy spectrum lead to unusual features in persistent current behavior. The variation of magnetic field or carrier concentration by means of gates can lead to pure spin persistent current with the charge current being zero.

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