Related papers: Electronic Shell Structure of Nanoscale Supercondu…
In recent experiments on nanoscale Al particles, whose electron number was fixed by charging effects, a ``negative gap'' was observed in particles with an odd number of electrons. This observation has called into question the use of a grand…
We combine the BCS self-consistency condition, a semiclassical expansion for the spectral density and interaction matrix elements to describe analytically how the superconducting gap depends on the size and shape of a 2d and 3d…
The canonical BCS wave function is tested for the attractive Hubbard model. Results are presented for one dimension, and are compared with the exact solutions by the Bethe ansatz and the results from the conventional grand canonical BCS…
We test the canonical BCS wave functions for fixed number of electrons for the attractive Hubbard model. We present results in one dimension for various chain lengths, electron densities, and coupling strengths. The ground-state energy and…
In a zero-dimensional superconductor, quantum size effects(QSE) not only set the limit to superconductivity, but are also at the heart of new phenomena such as shell effects, which have been predicted to result in large enhancements of the…
We study finite size effects in superconducting metallic grains and determine the BCS order parameter and the low energy excitation spectrum in terms of size, and shape of the grain. Our approach combines the BCS self-consistency condition,…
The existence of shell structure and the accompanying high degeneracy of electronic levels leads to the possibility of strong superconducting pairing in metallic nanoclusters with N~100-1000 delocalized electrons. The most favorable cases…
The existence of macroscopic shell structure of submicron metal clusters is known for several decades. Since the most studies provide theoretical analysis for clusters of spherical shape, the electron density inhomogeneities caused by shell…
The electronic properties of heterojunction electron gases formed in GaN/AlGaN core/shell nanowires with hexagonal and triangular cross-sections are studied theoretically. We show that at nanoscale dimensions, the non-polar hexagonal system…
The effects of long-range anisotropic elastic deformations on electronic structure in superconductors are analyzed within the framework of the Bogoliubov-de Gennes equations. Cases of twin boundaries and isolated defects are considered as…
Motivated by the recent observation of the shell effect in a nanoscale pure superconductor by Bose {\em et al} [Nat. Mat. {\bf 9}, 550 (2010)], we explore the possible shell-like effect in a strongly disordered superconductor as it is known…
The quantum states of a system of particles in a finite spatial domain in general consist of a set of discrete energy eigenvalues; these are usually grouped into bunches of degenerate or close-lying levels, called shells. In fermionic…
We report experiments on aluminum nanowires in ultra-high vacuum at room temperature that reveal a periodic spectrum of exceptionally stable structures. Two "magic" series of stable structures are observed: At low conductance, the formation…
We present a numerical simulation study of the exchange bias (EB) effect in nanoparticles with core/shell structure aimed to unveil the microscopic origin of some of the experimental phenomenology associated to this effect. In particular,…
Shell structure in the single particle spectrum of deformed harmonic oscillator potentials when a term proportional to $(\vec L)^2$ is added is analyzed for a large particle number. A scaling law which gives a dividing line between regular…
We investigate superconductivity in a grand canonical ensemble with {\it fixed number parity} (even or odd). In the low temperature limit we find small corrections to the BCS gap equation and energy spectrum $E(k)$. The even-odd free energy…
A theory of the long wavelength low energy electronic structure of graphite-derived nanotubules is presented. The propagating $\pi$ electrons are described by wrapping a massless two dimensional Dirac Hamiltonian onto a curved surface. The…
The recent advances in nanowire (NW) growth technology have made possible the growth of more complex structures such as core-multi-shell (CMS) NWs. We propose the approach for calculation of electron subbands in cylindrical CMS NWs within…
We predict enhanced electron-hole superfluidity in two coupled electron-hole armchair-edge terminated graphene nanoribbons separated by a thin insulating barrier. In contrast to graphene monolayers, the multiple subbands of the nanoribbons…
We study the effects of nanoscale impurity structures on the local electronic structure of $d_{x^2-y^2}$-wave superconductors. We show that the interplay between the momentum dependence of the superconducting gap, the geometry of the…