Persona:
Alvarellos Bermejo, José Enrique

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ORCID
0000-0003-2184-2787
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Proyectos de investigación
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Alvarellos Bermejo
Nombre de pila
José Enrique
Nombre

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2020 - 20233
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Fecha de finalización: 2023 × Fecha de inicio: 2020 ×

Resultados de la búsqueda

Mostrando 1 - 3 de 3
  • Miniatura
    Publicación
    Ergotropy and entanglement in critical spin chains
    (American Physical Society, 2023-02-08) Mula, Begoña; Fernández, Julio J.; Santalla, Silvia N.; Alvarellos Bermejo, José Enrique; García Aldea, David; Rodríguez Laguna, Javier; Fernández Sánchez, Evamaría
    A subsystem of an entangled ground state (GS) is in a mixed state. Thus, if we isolate this subsystem from its surroundings, we may be able to extract work applying unitary transformations, up to a maximal amount which is called ergotropy. Once this work has been extracted, the subsystem will still contain some bound energy above its local GS, which can provide valuable information about the entanglement structure. We show that the bound energy for half a free fermionic chain decays as the square of the entanglement entropy divided by the chain length, thus approaching zero for large system sizes, and we conjecture that this relation holds for all one-dimensional critical states.
  • Miniatura
    Publicación
    Melting in two-dimensional systems: Characterizing continuous and first-order transitions
    (American Physical Society, 2022-03-16) Toledano Sanz, Óscar; Pancorbo Castro, Manuel; Alvarellos Bermejo, José Enrique; Gálvez González, Óscar
    The mechanisms underlying the melting process in bidimensional systems have been widely studied by means of experiments, theory, and simulations since Kosterlitz, Thouless, Halperin, Nelson, and Young elaborated the KTHNY theory. In the framework of this theory, melting is produced by two continuous transitions mediated by the unbinding of local defects and the appearance of an intermediate phase between solid and liquid, called “hexatic.” There are also other competing theories that could explain this process, as, e.g., the formation of grain boundaries (lines of defects), which lead to a first-order transition. In this paper, simulations of systems interacting via the Lennard Jones 6–12 and Morse potentials using the Metropolis Monte Carlo method in the NVT ensemble have been performed to study the effect of the potential shape in the melting process. Additionally, truncated Morse potentials (with only a repulsive part) have been used to investigate the effect of the long-range interactions. Transitions from solid to hexatic phases were found to be continuous for all potentials studied, but transitions from hexatic to liquid phases were found to be either continuous or first order, depending on the thermodynamic conditions and the potential interaction selected, suggesting that melting can be triggered by different mechanisms, like grain boundary formation or defect unbinding. We find that the ratio of defects at the liquid-hexatic or liquid-coexistence phase transitions could determine the nature of these transitions and the mechanism underlying the melting process. The effect of the interaction of particles with their first- and second-nearest neighbors is also discussed.
  • Miniatura
    Publicación
    Nanowire reconstruction under external magnetic fields
    (AIP, 2020-12-23) Santalla, Silvia N.; Rodríguez Laguna, Javier; Fernández Sánchez, Evamaría; Alvarellos Bermejo, José Enrique; Rodríguez Laguna, Javier; Fernández Sánchez, Evamaría
    We consider the different structures that a magnetic nanowire adsorbed on a surface may adopt under the influence of external magnetic or electric fields. First, we propose a theoretical framework based on an Ising-like extension of the 1D Frenkel–Kontorova model, which is analyzed in detail using the transfer matrix formalism, determining a rich phase diagram displaying structural reconstructions at finite fields and an antiferromagnetic–paramagnetic phase transition of second order. Our conclusions are validated using ab initio calculations with density functional theory, paving the way for the search of actual materials where this complex phenomenon can be observed in the laboratory.