arXiv subjects

K. H. A. Villegas

Publications and source records attributed to K. H. A. Villegas.

4 recordsLinked to original sources

arXiv2021

Bose-Einstein condensate-mediated superconductivity in graphene

We propose a mechanism for robust BCS-like superconductivity in graphene placed in the vicinity of a Bose-Einstein condensate. Electrons in the graphene interact with the excitations above the condensate, called Bogoliubov quasiparticles (or bogolons). It turns out that bogolon-pair-mediated interaction allows us to surpass the long-standing problem of the vanishing density of states of particles with a linear spectrum. This results in a dramatic enhancement of the superconducting properties of graphene while keeping its relativistic dispersion. We study the behavior of the superconducting gap and calculate critical temperatures in cases with single-bogolon and bogolon-pair-mediated pairing processes, accounting for the complex band structure of graphene. We also compare the critical temperature of the superconducting transition with the BKT temperature.

cond-mat.supr-con↗

arXiv2021

Theory of BCS-like bogolon-mediated superconductivity in transition metal dichalcogenides

We report on a novel mechanism of BCS-like superconductivity, mediated by a pair of Bogoliubov quasiparticles (bogolons). It takes place in hybrid systems consisting of a two-dimensional electron gas in a transition metal dichalcogenide monolayer in the vicinity of a Bose-Einstein condensate. Taking a system of two-dimensional indirect excitons as a testing ground we show, that the bogolon-pair-mediated electron pairing mechanism is stronger than phonon-mediated and single bogolon-mediated ones. We develop a microscopic theory of bogolon-pair-mediated superconductivity, based on the Schrieffer-Wolff transformation and the Gor'kov's equations, study the temperature dependence of the superconducting gap and estimate the critical temperature of superconducting transition for various concentrations of the electron gas and the condensate densities.

cond-mat.supr-con↗

arXiv2018

Bogolon-mediated electron scattering in graphene in hybrid Bose-Fermi systems

We report on an unconventional mechanism of electron scattering in graphene in hybrid Bose- Fermi systems. We study energy-dependent electron relaxation time, accounting for the processes of emission and absorption of a Bogoliubov excitation (a bogolon). Then using the Bloch-Gruneisen approach, we find the finite-temperature resistivity of graphene and show that its principal behavior is $\sim T^4$ in the limit of low temperatures and linear at high temperatures. We show that bogolon-mediated scattering can surpass the acoustic phonon-assisted relaxation. It can be controlled by the distance between the layers and the condensate density, giving us additional degrees of freedom and a useful tool to render electron mobility by the sample design and external pump.

cond-mat.mes-hall↗

arXiv2018

Shedding light on topological superconductors

We propose an optical approach to monitor superconductors in conjunction with a normal metal layer. Effectively such a hybrid system represents a resonator, where electrons are strongly coupled with light. We show that the interaction of light with the superconductor turns out strongly boosted in the presence of the neighboring metal and as a result, the electromagnetic power absorption of the system is dramatically enhanced. It manifests itself in a giant Fanolike resonance which can uniquely characterize the elementary excitations of the system. Our approach is especially promising for topological superconductors, where the Majorana fermions can be revealed and controlled by light.

cond-mat.supr-con↗