Browsing by Author "Soto Garrido, Rodrigo"

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    Axionic quantum criticality of generalized Weyl semimetals
    (2025) Malavé, Gabriel; Soto Garrido, Rodrigo; Pontificia Universidad Católica de Chile. Facultad de Física
    In this work, we capture the quantum criticality of interacting generalized Weyl semimetals residing at the brink of axionic insulation. We do this by formulating a general field-theoretic description of $d$-dimensional interacting nodal semimetals featuring dispersion that scales with linear and $n$th power of momentum along $d_L$ and $d_M$ directions around a few isolated points in the reciprocal space. A suitable renormalization group scheme is controlled by ``small" parameters $\varepsilon=2-d_M$ and $1/N_f$, where $N_f$ is the number of identical fermion copies. The leading order renormalization group analysis suggests a Gaussian nature of the underlying quantum phase transition, around which the critical exponents assume mean-field values. This outcome agrees with previous results for simple Weyl semimetals ($d_L=3$ and $d_M=0$), and implies that marginal Fermi liquids showcase logarithmic corrections to physical observables at the scales of measurements.
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    Holographic description of an anisotropic Dirac semimetal
    (2024) Bahamondes, Sebastián; Salazar Landea, Ignacio; Soto Garrido, Rodrigo
    Holographic quantum matter exploits the AdS/CFT correspondence to study systems in condensed matter physics. An example of these systems are strongly correlated semimetals, which feature a rich phase diagram structure. In this work, we present a holographic model for a Dirac semimetal in 2 + 1 dimensions that features a topological phasetransition. Our construction relies on deforming a relativistic UV fixed point with some relevant operators that explicitly break rotations and some internal symmetries. The phase diagram for diferent values of the relevant coupling constants is obtained. The diferent phases are characterized by distinct dispersion relations for probe fermionic modes in theAdS geometry. We find semi-metallic phases characterized by the presence of Dirac conesand an insulating phase featuring a mass gap with a mild anisotropy. Remarkably, we find as well an anisotropic semi-Dirac phase characterized by a massless a fermionic excitation dispersing linearly in one direction while quadratically in the other.
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    Probing holographic flat bands at finite density
    (2024) Grandi, Nicolás; Juričić, Vladimir; Salazar Landea, Ignacio; Soto Garrido, Rodrigo
    Flat band electronic systems exhibit a rich landscape of correlation-driven phases, both at the charge neutrality and finite electronic density, featuring exotic electromagnetic and thermodynamic responses. Motivated by these developments, in this paper, we explicitly include the effects of the chemical potential in a holographic model featuring approximately flat bands. In particular, we explore the phase diagram of this holographic flat band system as a function of the chemical potential. We find that at low temperatures and densities, the system features a nematic phase, transitioning into the Lifshitz phase as the chemical potential or temperature increases. To further characterize the ensuing phases, we investigate the optical conductivity and find that this observable shows strong anisotropies in the nematic phase.
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    Thermal and quantum phase transitions in a holographic anisotropic Dirac semimetal: a theoretical model for semi-Dirac critical anisotropy in strongly interacting condensed matter using the AdS/CFT correspondence
    (2025) Bahamondes, Sebastián; Soto Garrido, Rodrigo; Pontificia Universidad Católica de Chile. Instituto de Física
    En esta tesis se construyó un modelo teórico de un sistema fuertemente interactuante en 2+1-dimensiones a través de la correspondencia holográfica AdS/CFT. En dicho modelo se detectó, mediante técnicas numéricas y analíticas, una transición de fase tipo semi-Dirac a temperatura cero y temperatura finita. Además, se identificó la transición de temperatura cero como una transición de fase cuántica mediante el escaleo del ratio de viscosidad-densidad de entropía a bajas temperaturas. Además, se comprobó que este modelo rompe la cota KSS propuesta por Kovtun, Son y Starinets, lo cual añade este modelo a la expansiva literatura de modelos holográficos que violan dicha cota.
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    Thermo-Magneto-Electric Transport through a Torsion Dislocation in a Type I Weyl Semimetal
    (2021) Bonilla Moreno, Daniel; Muñoz, Enrique; Soto Garrido, Rodrigo
    Herein, we study electronic and thermoelectric transport in a type I Weyl semimetal nanojunction, with a torsional dislocation defect, in the presence of an external magnetic field parallel to the dislocation axis. The defect is modeled in a cylindrical geometry, as a combination of a gauge field accounting for torsional strain and a delta-potential barrier for the lattice mismatch effect. In the Landauer formalism, we find that due to the combination of strain and magnetic field, the electric current exhibits chiral valley-polarization, and the conductance displays the signature of Landau levels. We also compute the thermal transport coefficients, where a high thermopower and a large figure of merit are predicted for the junction.