arXiv subjects

F. Dominguez

Publications and source records attributed to F. Dominguez.

8 recordsLinked to original sources

arXiv2025

Magnetic field-bias current interplay in HgTe-based three-terminal Josephson junctions

We investigate HgTe/Nb-based three-terminal Josephson junctions in T-shaped and X-shaped geometries and their critical current contours (CCCs). By decomposing the CCCs into the contributions from individual junctions, we uncover how bias current and magnetic field jointly determine the collective Josephson behavior. A perpendicular magnetic field induces a tunable crossover between SQUID-like and Fraunhofer-like interference patterns, controlled by the applied bias. Moreover, magnetic flux produces pronounced deformations of the CCC, enabling symmetry control in the $(I_1,I_2)$ plane. Remarkably, we identify a regime of strongly enhanced Josephson diode efficiency, reaching values up to $\eta\approx 0.8$ at low bias and magnetic field. The experimental results are quantitatively reproduced by resistively shunted junction (RSJ) simulations, which capture the coupled dynamics of current and flux in these multi-terminal superconducting systems.

cond-mat.supr-con↗

arXiv2024

Effects of spin-orbit coupling in a valley chiral kagom\'e network

Valley chiral kagom\'e networks can arise in various situations, like for example, in double-aligned graphene-hexagonal boron nitride and periodically strained graphene. Here, we construct a phenomenological scattering model based on the symmetries of the network to investigate the energy spectrum and magnetotransport in this system. Additionally, we consider the effects of a finite Rashba spin-orbit coupling on the transport properties of the kagom\'e network. We identify conditions where the interplay of the Rashba spin-orbit coupling and the geometry of the lattice results in a reduction of the periodicity of the magnetoconductance and characteristic sharp resonances. Moreover, we find a finite spin-polarization of the conductance, which could be exploited in spintronic devices.

cond-mat.mes-hall↗

arXiv2023

Localized states coupled to a network of chiral modes in minimally twisted bilayer graphene

Minimally twisted bilayer graphene in the presence of an interlayer bias develops a triangular network of valley chiral modes that propagate along the $AB/BA$ interfaces and scatter at the $AA$ regions. The low energy physics of the resulting network can be captured by means of a phenomenological scattering network model, allowing to calculate the energy spectrum and the magnetoconductance in a straightforward way. Although there is in general a good agreement between microscopic and phenomenological models, there are some aspects that have not been captured so far with the latter. In particular, the appearance of flatbands in the energy spectrum associated to a localized density of states at the $AA$ regions. To bring both approaches closer together, we modify the previous energy independent phenomenological model and add the possibility to scatter to a set of discrete energy levels at the $AA$ regions, yielding a $S$ matrix with energy dependent parameters. Furthermore, we investigate the impact of Coulomb repulsion in these regions on a mean-field level and discuss possible effects of decoherence due to elastic and inelastic cotunneling events.

cond-mat.mes-hall↗

arXiv2022

Fraunhofer pattern in the presence of Majorana zero modes

We propose a new platform to detect signatures of the presence of Majorana bound states (MBSs) in the Fraunhofer pattern of Josephson junctions featuring quantum spin Hall edge states on the normal part and Majorana bound states at the NS interfaces. We use a tight-binding model to demonstrate a drastic change in the periodicity of the Fraunhofer pattern when comparing trivial and non-trivial regimes. We explain these results in terms of the presence of additional parallel-spin electron-hole reflections, which due to the spin-momentum locking, occur as cross Andreev reflections, accumulating a different magnetic flux and yielding a change in the Fraunhofer periodicity. We show that this detection scheme exhibits some advantages compared to previous ones as it is robust against disorder, finite temperature and works in equilibrium. Furthermore, we introduce a scattering model that captures the main results of the microscopic calculations with MBSs and extend our discussion to the main differences found using accidental zero energy ABSs.

cond-mat.mes-hall↗

arXiv2020

Chiral zigzag modes and flatbands in network models of twisted bilayer graphene

We construct a phenomenological scattering theory for the triangular network of valley Hall states that arises in twisted bilayer graphene under interlayer bias. Crucially, our network model includes scattering between different valley Hall states within the same valley and spin. We show that in the absence of forward scattering, symmetries reduce the network model to a single parameter that interpolates between a nested Fermi surface and flatbands, which can be understood in terms of one-dimensional chiral zigzag modes and closed triangular orbits, respectively. We demonstrate how unitarity and symmetry constrain the couplings between zigzag modes, which has important implications on the nature of interference oscillations observed in experiments.

cond-mat.mes-hall↗

arXiv2011

Gluons and the quark sea at high energies: distributions, polarization, tomography

This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics. This report is organized around four major themes: i) the spin and flavor structure of the proton, ii) three-dimensional structure of nucleons and nuclei in momentum and configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC.

nucl-th↗

arXiv2011

Gluon saturation effects on the color singlet J/Psi production in high energy dA and AA collisions

We derive the formulae for the cross section of J/Psi production in high energy pA and AA collisions taking into account the gluon saturation/color glass condensate effects. We then perform the numerical calculations of the corresponding nuclear modification factors and find a good agreement between our calculations and the experimental data on J/Psi production in dA collisions. We also observe that cold nuclear modification effects alone cannot describe the data on J/Psi production in AA collisions. Additional final state suppression (at RHIC) and enhancement (at LHC) mechanisms are required to explain the experimental observations.

hep-ph↗

arXiv2006

Solving the Richardson equations close to the critical points

We study the Richardson equations close to the critical values of the paring strength g_c where the occurrence of divergencies preclude numerical solutions. We derive a set of equations for determining the critical g values and the non-collapsing pair energies. Studying the behavior of the solutions close to the critical points, we develop a procedure to solve numerically the Richardson equations for arbitrary coupling strength.

math-ph↗