Evidence of weak ferromagnetism in doped plasticized polyaniline (PANI-DDoESSA)0.5 from electron spin resonance measurements

X-band electron spin resonance (ESR) measurements have been performed on a conducting free-standing film of polyaniline plasticized and protonated with di-n-dodecyl ester of sulfosuccinic acid (DDoESSA). The magnetic field was applied parallel and perpendicular to the plane of the film. At around 75 K a transition is observed from Pauli susceptibility to a localized state in which the spin 1/2 polarons behave as spin 1/2 dimers. A rough estimation of the intradimer and interdimer exchange constants is obtained. Below 5 K, ESR data reveal a weak ferromagnetism with the Dzyaloshinskii-Moriya vector mainly oriented in the plane of the film. The existence of a relatively well-defined n-fold axis along the chain direction in the crystalline regions confers a symmetry compatible with such analysis. © 2013 IOP Publishing Ltd.

Chiral symmetry, massive gluons and confinement

It is quite difficult to obtain non-trivial chiral symmetry breaking solutions for the quark gap equation in the presence of dynamically generated gluon masses. An effective confining propagator has recently been proposed by Cornwall in order to solve this problem. We study phenomenological consequences of this approach, showing its compatibility with the experimental data. We argue that this confining propagator should be restricted to a small region of momenta, leading to effective four-fermion interactions at low energy. © 2013 American Institute of Physics.

Massive spin-2 particle from a rank-2 tensor

Here we obtain all possible second-order theories for a rank-2 tensor which describe a massive spin-2 particle. We start with a general second-order Lagrangian with ten real parameters. The absence of lower-spin modes and the existence of two local field redefinitions leads us to only one free parameter. The solutions are split into three one-parameter classes according to the local symmetries of the massless limit. In the class which contains the usual massive Fierz-Pauli theory, the subset of spin-1 massless symmetries is maximal. In another class where the subset of spin-0 symmetries is maximal, the massless theory is invariant under Weyl transformations and the mass term does not need to fit into the form of the Fierz-Pauli mass term. In the remaining third class neither the spin-1 nor the spin-0 symmetry is maximal and we have a new family of spin-2 massive theories. © 2013 American Physical Society.

Medidas de ressonância de spin eletrônico (RSE) em polianilina dopada com plastificante e de condutividade a.c. e RSE em óxidos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Exploring teleparallel dark energy

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Graphene sheet versus two-dimensional electron gas: A relativistic Fano spin filter via STM and AFM tips

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Light-Induced Structural Change in Iridium Complexes Studied by Electron Spin Resonance

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Mylar Secondary Emission-energy Distribution and Yields

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Three-point functions and su(1 vertical bar 1) spin chains

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Application of effective theory and Grassmann variables to model compact binaries with spin

Pós-graduação em Física - IFT

Dirac gaugions, R symmetry and the 125 GeV Higgs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mobile vector soliton in a spin-orbit coupled spin-1 condensate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Temperature-induced spontaneous time-reversal symmetry breaking on the honeycomb lattice

Phase transitions involving spontaneous time-reversal symmetry breaking are studied on the honeycomb lattice at finite hole doping with next-nearest-neighbor repulsion. We derive an exact expression for the mean-field equation of state in closed form, valid at temperatures much less than the Fermi energy. Contrary to standard expectations, we find that thermally induced intraband particle-hole excitations can create and stabilize a uniform metallic phase with broken time-reversal symmetry as the temperature is raised in a region where the ground state is a trivial metal.

Improved electrical transport in lightly Er-doped sol-gel spin-coating SnO2 thin films, processed by photolithography

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Higher spin constraints and the super (W∞/2 ⊕ W1+∞/2) algebra in the super eigenvalue model

We show that the partition function of the super eigenvalue model satisfies, for finite N (non-perturbatively), an infinite set of constraints with even spins s = 4, 6, . . . , ∞. These constraints are associated with half of the bosonic generators of the super (W∞/2 ⊕ W1+∞/2) algebra. The simplest constraint (s = 4) is shown to be reducible to the super Virasoro constraints, previously used to construct the model.