arXiv subjects

J. D. Lejarreta

Publications and source records attributed to J. D. Lejarreta.

5 recordsLinked to original sources

arXiv2018

Quantized electron transport through graphene nanoconstrictions

We study the quantization of Dirac fermions in lithographically defined graphene nanoconstrictions. We observe quantized conductance in single nanoconstrictions fabricated on top of a thin hexamethyldisilazane layer over a Si/SiO_2 wafer. This nanofabrication method allows us to obtain well defined edges in the nanoconstrictions, thus reducing the effects of edge roughness on the conductance. We prove the occurrence of ballistic transport and identify several size quantization plateaus in the conductance at low temperature. Experimental data and numerical simulations show good agreement, demonstrating that the smoothing of the plateaus is not related to edge roughness but to quantum interference effects.

cond-mat.mes-hall↗

arXiv2015

Iterative symmetry search and reduction of a wave water model in $2+1$ dimensions

We present the iterative classical point symmetry analysis of a shallow water wave equation in $2+1$ dimensions and that of its corresponding nonisospectral, two component Lax pair. A few reductions arise and are identified with celebrate equations in the Physics and Mathematics literature of nonlinear waves. We pay particular attention to the isospectral or nonisospectral nature of the reduced spectral problems.

nlin.SI↗

arXiv2015

Integrable $1+1$ dimensional hierarchies arising from the reduction of a nonisospectral problem in $2+1$ dimensions

This work presents a classical Lie point symmetry analysis of a two-component, non-isospectral Lax pair of a hierarchy of partial differential equations in $2+1$ dimensions, which can be considered as a modified version of the Camassa-Holm hierarchy in $2+1$ dimensions. A classification of reductions for this spectral problem is performed. Non-isospectral reductions in $1+1$ dimensions are considered of remarkable interest.

math-ph↗

arXiv2012

Angle dependent conductance in graphene

In this paper, we study a theoretical method to calculate the conductance across a square barrier potential in monolayer graphene. We have obtained an analytical expression for the transmission coefficient across a potential barrier for monolayer graphene. Using the transmission coefficient obtained we have an analytical expression for the conductance. This expression will be used to calculate the conductance in the case in which there is a potential barrier, which in our case will modelise the behaviour of a top gate voltage of a field effect transistor. Once this analysis has been performed we study the scenario in which carriers scatter with the potential barrier with different incidence angles and we have found that for any incident angle an effective gap is induced.

cond-mat.mes-hall↗

arXiv2001

Intense laser interacting with a two level atom: WKB expressions for dipole transitions and population inversion

In a previous paper, we have already considered the system composed by a two level atom interacting with a coherent external electromagnetic field. No application whatsoever has been made of the rotating wave approximation. Being specially interested in the problem of higher harmonic generations for the case of very intense laser fields, we have developed in this letter a much more efficient way to obtain these solutions as well as to carry out some calculations in a range in which the parameters take extreme values. Also the formalism allows us now to provide analytic expressions in the WKB regime for the electric dipole moment and the population inversion. The spectrum can be decomposed in periodic and non-periodic contributions. Only the latter depends upon the Floquet exponent and can be responsible of the main complexities of the observed Rabi revivals and the hyper-Raman shift.

quant-ph↗