Publicación de nuevo artículo por parte de miembros del departamento de física aplicada.
We report on the fabrication, transport measurements, and density functional theory (DFT) calculations of atomic-size contacts made of gadolinium (Gd). Gd is known to have local moments mainly associated with f electrons. These coexist with itinerant s and d bands that account for its metallic character. Here we explore whether and how the local moments influence electronic transport properties at the atomic scale. Using both scanning tunneling microscope and lithographic mechanically controllable break junction techniques under cryogenic conditions, we study the conductance of Gd when only few atoms form the junction between bulk electrodes made of the very same material. Thousands of measurements show that Gd has an average lowest conductance, attributed to single-atom contact, below 2e2h. Our DFT calculations for monostrand chains anticipate that the f bands are fully spin polarized and insulating and that the conduction may be dominated by s, p, and d bands. We also analyze the electronic transport for model nanocontacts using the nonequilibrium Green's function formalism in combination with DFT. We obtain an overall good agreement with the experimental results for zero bias and show that the contribution to the electronic transport from the f channels is negligible and that from the d channels is marginal.
B. Olivera, C. Salgado, J. L. Lado, A. Karimi, V. Henkel, E. Scheer, J. Fernández-Rossier, J. J. Palacios, and C. Untiedt Phys. Rev. B 95, 075409 – Published 8 February 2017
Elecciones a Director/a de Departamento 2017
En el Consejo Extraordinario del Departamento de Física Aplicada celebrado el día 17 de enero de 2017 se ha aprobado la convocatoria de elecciones a director/a del departamento y el calendario electoral.
SEMINARIO: "HADRON SPECTROSCOPY: FROM THE RHO MESON TO MULTIQUARK STATES WITH HEAVY QUARKS"
Impartido por: Raquel Molina Peralta, The George Washington University
Fecha y hora: Jueves, 12 de enero de 2017 a las 12:30 horas
Lugar: Sala Polivalente del Departamento de Física Aplicada, Facultad de Ciencias, Fase II
Quantum Chromodynamics (QCD) is the theory of the strong interaction, one of the fundamental forces of nature, which is responsible for the properties of microscopic matter as we know it. In the intermediate energy region, QCD manifests itself in a very rich and complex spectrum of resonances. Lattice QCD calculations have recently contributed signi_cantly to the extraction of resonance phase shifts from _rst principles of QCD. E_ective eld theories can be adapted to the conditions of the _nite volume and are useful to analyze the quark mass dependence and the e_ect of missing channels. In the _rst part of this talk, lattice QCD data on p-wave __ scattering are analyzed with Unitary Chiral Perturbation Theory. The analysis shows that the kaon channel pushes upward the __ scattering phase shift having an e_ect on the _-mass. Some examples of likely candidates for multiquark states in the light-quark sector are given. On the second part of the talk, charm spectroscopy is reviewed. The B factories, originally constructed to test CP violation, have discovered a plethora of states called XYZ di_cult to interpreted in terms of q_q. The charged charmonia Z observed by BESIII are clearly candidates to be tetraquarks or two-meson molecules. LHCb, has observed recently a pentaquark state decaying into J p. The need of understanding the strong interaction has motivated experiments to collect an unprecedented amount of data on hadron spectroscopy, and the spectrum is evolving into an extraordinary complexity, which urges the theory community to make e_orts to understand the nature of these new particles. Chiral lagrangians and hidden gauge approaches give us some clues on the nature of these exotic states near thresholds.
Isabel Abril, catedrática del departamento de física aplicada de la Universidad de Alicante desarrolla una investigación básica que busca obtener modelos más eficaces y completos para el tratamiento contra el cáncer con haces de iones de muy alta energía, una técnica que podría sustituir o complementar a la radioterapia convencional.