DSpace Communidade:
http://repositorio.ufla.br/jspui/handle/1/4639
2018-02-02T08:41:09ZRelativistic quantum dynamics of a neutral particle in external electric fields: an approach on effects of spin
http://repositorio.ufla.br/jspui/handle/1/13428
Título: Relativistic quantum dynamics of a neutral particle in external electric fields: an approach on effects of spin
Autor: Azevedo, F. S.; Silva, Edilberto O.; Castro, Luis B.; Filgueiras, Cleverson; Cogollo, D.
Resumo: The planar quantum dynamics of a spin-1/2 neutral particle interacting with electrical fields is considered. A set of first order differential equations is obtained directly from the planar Dirac equation with nonminimum coupling. New solutions of this system, in particular, for the Aharonov–Casher effect, are found and discussed in detail. Pauli equation is also obtained by studying the motion of the particle when it describes a circular path of constant radius. We also analyze the planar dynamics in the full space, including the r=0 region. The self-adjoint extension method is used to obtain the energy levels and wave functions of the particle for two particular values for the self-adjoint extension parameter. The energy levels obtained are analogous to the Landau levels and explicitly depend on the spin projection parameter.2015-11-01T00:00:00ZQuantum motion of a point particle in the presence of the Aharonov–Bohm potential in curved space
http://repositorio.ufla.br/jspui/handle/1/13427
Título: Quantum motion of a point particle in the presence of the Aharonov–Bohm potential in curved space
Autor: Silva, Edilberto O.; Ulhoa, Sérgio C.; Andrade, Fabiano M.; Filgueiras, Cleverson; Amorim, R. G. G.
Resumo: The nonrelativistic quantum dynamics of a spinless charged particle in the presence of the Aharonov–Bohm potential in curved space is considered. We chose the surface as being a cone defined by a line element in polar coordinates. The geometry of this line element establishes that the motion of the particle can occur on the surface of a cone or an anti-cone. As a consequence of the nontrivial topology of the cone and also because of two-dimensional confinement, the geometric potential should be taken into account. At first, we establish the conditions for the particle describing a circular path in such a context. Because of the presence of the geometric potential, which contains a singular term, we use the self-adjoint extension method in order to describe the dynamics in all space including the singularity. Expressions are obtained for the bound state energies and wave functions.2015-11-01T00:00:00Z2DEG on a cylindrical shell with a screw dislocation
http://repositorio.ufla.br/jspui/handle/1/13426
Título: 2DEG on a cylindrical shell with a screw dislocation
Autor: Filgueiras, Cleverson; Silva, Edilberto O.
Resumo: A two dimensional electron gas on a cylindrical surface with a screw dislocation is considered. More precisely, we investigate how both the geometry and the deformed potential due to a lattice distortion affect the Landau levels of such system. The case showing the deformed potential can be thought in the context of 3D common semiconductors where the electrons are confined on a cylindrical shell. We will show that important quantitative differences exist due to this lattice distortion. For instance, the effective cyclotron frequency is diminished by the deformed potential, which in turn enhances the Hall conductivity.2015-09-25T00:00:00ZInfluence of spatially varying pseudo-magnetic field on a 2D electron gas in graphene
http://repositorio.ufla.br/jspui/handle/1/13425
Título: Influence of spatially varying pseudo-magnetic field on a 2D electron gas in graphene
Autor: Leite, L. G. da Silva; Filgueiras, C.; Cogollo, D.; Silva, Edilberto O.
Resumo: The effect of a varying pseudo-magnetic field, which falls as 1/x2, on a two-dimensional electron gas in graphene is investigated. By considering the second order Dirac equation, we show that its correct general solution is that which might present singular wavefunctions since such field induced by elastic deformations diverges as x→0. We show that only this consideration yields the known relativistic Landau levels when we remove such elastic field. We have observed that the zero Landau level fails to develop for certain values of it. We then speculate about the consequences of these facts to the quantum Hall effect on graphene. We also analyze the changes in the relativistic cyclotron frequency. We hope our work is being probed in these contexts, since graphene has great potential for electronic applications.2015-05-08T00:00:00Z