arXiv subjects

Manuel Barranco

Publications and source records attributed to Manuel Barranco.

43 records · Page 3Linked to original sources

arXiv2000

Pinning of quantized vortices in helium drop by dopant atoms and molecules

Using a density functional method, we investigate the properties of liquid 4He droplets doped with atoms (Ne and Xe) and molecules (SF_6 and HCN). We consider the case of droplets having a quantized vortex pinned to the dopant. A liquid drop formula is proposed that accurately describes the total energy of the complex and allows one to extrapolate the density functional results to large N. For a given impurity, we find that the formation of a dopant+vortex+4He_N complex is energetically favored below a critical size N_cr. Our result support the possibility to observe quantized vortices in helium droplets by means of spectroscopic techniques.

cond-mat↗

arXiv1999

Far-infrared spectroscopy of nanoscopic InAs rings

We have employed time-dependent local-spin density theory to analyze the far-infrared transmission spectrum of InAs self-assembled nano-rings recently reported [A. Lorke et al, cond-mat/9908263 (1999)]. The overall agreement between theory and experiment is good, which on the one hand confirms that the experimental peaks indeed reflect the ring-like structure of the sample, and on the other hand, asseses the suitability of the theoretical method to describe such small nanostructures. The addition energies of one- and two-electron rings are also reported and compared with the corresponding capacitance spectra.

cond-mat↗

arXiv1999

Wave-vector dependence of spin and density multipole excitations in quantum dots

We have employed time-dependent local-spin density functional theory to analyze the multipole spin and charge density excitations in GaAs-AlGaAs quantum dots. The on-plane transferred momentum degree of freedom has been taken into account, and the wave-vector dependence of the excitations is discussed. In agreement with previous experiments, we have found that the energies of these modes do not depend on the transferred wave-vector, although their intensities do. Comparison with a recent resonant Raman scattering experiment [C. Schüller et al, Phys. Rev. Lett {\bf 80}, 2673 (1998)] is made. This allows to identify the angular momentum of several of the observed modes as well as to reproduce their energies.

cond-mat.mes-hall↗

arXiv1999

Quantum cavitation in liquid $^3$He: dissipation effects

We have investigated the effect that dissipation may have on the cavitation process in normal liquid $^3$He. Our results indicate that a rather small dissipation decreases sizeably the quantum-to-thermal crossover temperature $T^*$ for cavitation in normal liquid $^3$He. This is a possible explanation why recent experiments have not yet found clear evidence of quantum cavitation at temperatures below the $T^*$ predicted by calculations which neglect dissipation.

cond-mat↗

arXiv1998

The structure of large 3He-4He mixed drops around a dopant molecule

We have investigated how helium atoms are distributed within a mixed $^3$He$_{N_3}$-$^4$He$_{N_4}$ large drop with $N_3 \gg N_4$. For drops doped with a SF$_6$ molecule or a Xe atom, we have found that the number of $^3$He atoms within the volume containing the first two solvation shells increases when $N_4$ decreases in a way such that these dopants may be in a superfluid environment for $N_4 \geq$ 60, which gradually disappears as $N_4$ decreases. The result is in qualitative agreement with recent experimental data.

cond-mat↗

arXiv1998

Structure and far-infrared edge modes of quantum antidots at zero magnetic field

We have investigated edge modes of different multipolarity sustained by quantum antidots at zero magnetic field. The ground state of the antidot is described within a local density functional formalism. Two sum rules, which are exact within this formalism, have been derived and used to evaluate the energy of edge collective modes as a function of the surface density and the size of the antidot.

cond-mat↗

arXiv1997

Current Density Functional approach to large quantum dots in intense magnetic fields

Within Current Density Functional Theory, we have studied a quantum dot made of 210 electrons confined in a disk geometry. The ground state of this large dot exhibits some features as a function of the magnetic field (B) that can be attributed in a clear way to the formation of compressible and incompressible states of the system. The orbital and spin angular momenta, the total energy, ionization and electron chemical potentials of the ground state, as well as the frequencies of far-infrared edge modes are calculated as a function of B, and compared with available experimental and theoretical results.

cond-mat↗