Browsing by Author "Castaño Yepes, Jorge David"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Electromagnetic coupling and transport in a topological insulator–graphene heterostructure
    (2023) Bonilla Moreno, Daniel; Castaño Yepes, Jorge David; Martín Ruiz, A.; Muñoz, Enrique
    The electromagnetic coupling between heterostructures made of different materials is of great interest, both from the perspective of discovering new phenomena, as well as for its potential applications in novel devices. In this work, we study the electromagnetic coupling of a heterostructure made of a topological insulator (TI) slab and a single graphene layer, where the later presents a diluted concentration of ionized impurities. We explore the topological effects of the magnetoelectric polarizability of the TI, as well as its relative dielectric permittivity on the electrical conductivity in graphene at low but finite temperatures.
  • Thumbnail Image
    Item
    Inversion Symmetry Breaking in the Probability Density by Surface‐Bulk Hybridization in Topological Insulators
    (2024) Castaño Yepes, Jorge David; Muñoz Tavera, Enrique
    The probability density distribution is analyzed in a topological insulator (TI) slab of finite thickness, where the bulk and surface states are allowed to hybridize. By using an effective continuum Hamiltonian approach as a theoretical framework, the wave functions are analytically obtained for each state near the -point. The results reveal that, under particular combinations of the hybridized bulk and surface states, the spatial symmetry of the electronic probability density with respect to the center of the slab can be spontaneously broken. This symmetry breaking arises as a combination of the parity of the solutions, their spin projection, and the material constants.
  • Thumbnail Image
    Item
    Temperature fluctuations in a relativistic gas: Pressure corrections and possible consequences in the deconfinement transition
    (2024) Castaño Yepes, Jorge David; Loewe, Marcelo; Muñoz, Enrique; Rojas Gómez-Lobo, Juan Cristóbal
    In this work, we study the effects of random temperature fluctuations on the partition function of a quantum system by means of the replica method. This picture provides a conceptual model for a quantum nonequilibrium system, depicted as an ensemble of subsystems at different temperatures, randomly distributed with respect to a given mean value. We then assume the temperature displays stochastic fluctuations T ¼ T0 þ δT with respect to its ensemble average value T0, with zero mean standard deviation δT ¼0 and δT2 ¼ Δ. By means of the replica method, we obtain the average grand canonical potential, leading to the equation of state and the corresponding excess pressure caused by these fluctuations with respect to the equilibrium system at a uniform temperature. Our findings reveal an increase in pressure as the system’s ensemble average temperature T0 rises, consistently exceeding the pressure observed in an equilibrium state. We applied our general formalism to three paradigmatic physical systems; the relativistic Fermi gas, the ideal gas of photons, and a gas of non-Abelian gauge fields (gluons) in the noninteracting limit. Finally, we explore the implications for the deconfinement transition in the context of the simple bag model, where we show that the critical temperature decreases.