Incipient quantum melting of the one-dimensional Wigner lattice

A one--dimensional tight--binding model of electrons with long--range Coulomb interactions is studied in the limit where double site occupancy is forbidden and the Coulomb coupling strength $V$ is large with respect to the hopping amplitude $t$. The quantum problem of a kink--antikink pair generated in the Wigner lattice (the classical ground state for $t=0$) is solved for fillings $n=1/s$, where $s$ is an integer larger than 1. The pair energy becomes negative for a relatively high value of $V$, $V_c/t\approx s^3$. This signals the initial stage of the quantum melting of the Wigner lattice

Variational Wave Function for Generalized Wigner Lattices in One Dimension

We study a system of electrons on a one-dimensional lattice, interacting through the long range Coulomb forces, by means of a variational technique which is the strong coupling analog of the Gutzwiller approach. The problem is thus the quantum version of Hubbard's classical model of the generalized Wigner crystal [J. Hubbard, Phys. Rev. B 17, 494 (1978)]. The magnetic exchange energy arising from quantum fluctuations is calculated, and turns out to be smaller than the energy scale governing charge degrees of freedom. This approach could be relevant in insulating quasi-one-dimensional compounds where the long range Coulomb interactions are not screened. In these compounds charge order often appears at high temperatures and coexists with magnetic order at low temperatures.Comment: 4 pages, proceedings of ECRYS-200

Bosonized supersymmetry from the Majorana-Dirac-Staunton theory and massive higher-spin fields

We propose a (3+1)D linear set of covariant vector equations, which unify the spin 0 ``new Dirac equation'' with its spin 1/2 counterpart, proposed by Staunton. Our equations describe a spin (0,1/2) supermultiplet with different numbers of degrees of freedom in the bosonic and fermionic sectors. The translation-invariant spin deegres of freedom are carried by two copies of the Heisenberg algebra. This allows us to realize space-time supersymmetry in a bosonized form. The grading structure is provided by an internal reflection operator. Then the construction is generalized by means of the Majorana equation to a supersymmetric theory of massive higher-spin particles. The resulting theory is characterized by a nonlinear symmetry superalgebra, that, in the large-spin limit, reduces to the super-Poincare algebra with or without tensorial central charge.Comment: 21 pages; refs added, version accepted for publication in Physical Review

Supersymmetry between Jackiw-Nair and Dirac-Majorana anyons

The Jackiw-Nair description of anyons combines spin-1 topologically massive fields with the discrete series representation of the Lorentz algebra, which has fractional spin. In the Dirac-Majorana formulation the spin-1 part is replaced by the spin 1/2 planar Dirac equation. The two models are shown to belong to an N=1 supermultiplet, which carries a super-Poincare symmetry.Comment: 4 pages, no figures. Typos corrected. Published versio

Measuring the interaction force between a high temperature superconductor and a permanent magnet

Repulsive and attractive forces are both possible between a superconducting sample and a permanent magnet, and they can give place to magnetic levitation or free-suspension phenomena, respectively. We show experiments to quantify this magnetic interaction which represents a promising field regarding to short-term technological applications of high temperature superconductors. The measuring technique employs an electronic balance and a rare-earth magnet that induces a magnetic moment in a melt-textured YBa2Cu3O7 superconductor immersed in liquid nitrogen. The simple design of the experiments allows a fast and easy implementation in the advanced physics laboratory with a minimum cost. Actual levitation and suspension demonstrations can be done simultaneously as a help to interpret magnetic force measurements.Comment: 12 pages and 3 figures in postscrip

Oscillatory dynamics of a superconductor vortex lattice in high amplitude ac magnetic fields

In this work we study by ac susceptibility measurements the evolution of the solid vortex lattice mobility under oscillating forces. Previous work had already shown that in YBCO single crystals, below the melting transition, a temporarily symmetric magnetic ac field (e.g. sinusoidal, square, triangular) can heal the vortex lattice (VL) and increase its mobility, but a temporarily asymmetric one (e.g. sawtooth) of the same amplitude can tear the lattice into a more pinned disordered state. In this work we present evidence that the mobility of the VL is reduced for large vortex displacements, in agreement with predictions of recent simulations. We show that with large symmetric oscillating fields both an initially ordered or an initially disordered VL configuration evolve towards a less mobile lattice, supporting the scenario of plastic flow.Comment: 5 pages, 4 figures. To appear in Phys. Rev.

Against wasted politics: a critique of the circular economy

The discourse of zero-waste and the circular economy has been championed by key players, such as the European Commission, management consultancies, NGOs, academics and multinational companies, in recent years. Given the all too obvious social and environmental crises associated with out-of-bounds growth capitalism, the circular economy has been one of the main references for rebuilding and reforming a political economy of sustainable growth. In this paper we detect a de-politicizing strategy in this attempt of reform, and, consequently, aim at re-locating a position for the politicization of growth-driven capitalism and the circular economy. We do this by offering a unique discursive-material theoretical framework, bringing together Marxist and Lacanian psychoanalytic readings. This will allow understanding both the subjective relation with the meaning of waste and the material exchanges that place the subject in the position to produce and consume waste as a valuable commodity. In our quest to (re-)politicize waste, we offer three practical steps that aim at interrupting the endless repetition of waste, which include attempts to eradicate it. This argument will be illustrated by making reference to the circular strategies of Apple Inc., the world’s largest and most iconic consumer electronics company