arXiv subjects

Karol. I. Wysokinski

Publications and source records attributed to Karol. I. Wysokinski.

4 recordsLinked to original sources

arXiv2018

Two interacting current model of holographic Dirac fluid in graphene

The electrons in graphene for energies close to the Dirac point have been found to form strongly interacting fluid. Taking this fact into account we have extended previous work on the transport properties of graphene by taking into account possible interactions between the currents and adding the external magnetic field directed perpendicularly to the graphene sheet. The perpendicular mag- netic field B severely modifies the transport parameters. In the present approach the quantization of the spectrum and formation of Landau levels is ignored. Gauge/gravity duality has been used in the probe limit. The dependence on the charge density of the Seebeck coefficient and thermo-electric parameters αij nicely agree with recent experimental data for graphene. The holographic model allows for the interpretation of one of the fields representing the currents as resulting from the dark matter sector. For the studied geometry with electric field perpendicular to the thermal gradient the effect of dark sector has been found to modify the transport parameters but mostly in a quantitative way only. This makes difficult the detection of this elusive component of the Universe by studying transport properties of graphene.

hep-th↗

arXiv2017

Holographic calcualtion of the magneto-transport coefficients in Dirac semimetals

Based on the gauge/gravity correspondence we have calculated the thermoelectric kinetic and transport characteristics of the strongly interacting materials in the presence of perpendicular magnetic field. The 3+1 dimensional system with Dirac-like spectrum is considered as a strongly interacting one if it is close to the particle-hole symmetry point. Transport in such system has been modeled by the two interacting vector fields. In the holographic theory the momentum relaxation is caused by axion field and leads to finite values of the direct current transport coefficients. We have calculated conductivity tensor in the presence of mutually perpendicular electric and magnetic fields and temperature gradient. The geometry differs from that in which magnetic field lies in the same plane as an electric one and temperature gradient.

hep-th↗

arXiv2016

Viscosity of holographic fluid in the presence of dark matter sector

Based on the gauge/gravity correspondence, the hydrodynamic response coefficients, shear and Hall viscosities, have been studied. The holographic model of Einstein-Maxwell- AdS $(3+1)$-dimensional system additionally coupled with the another gauge field mimicking the {\it dark matter} sector, as well as, gravitational Chern-Simons term bounded with a dynamical scalar field, were taken into account. Condensation of the scalar field provides the parity violating term. Both shear and Hall viscosities have been calculated and their dependence on $α$ - the coupling constant between matter and {\it dark matter} sectors has been studied. To the lowest order in the derivative expansion and perturbation in $α$, the shear viscosity is not influenced by the {\it dark matter}, while the Hall component linearly depends on $α$.

hep-th↗

arXiv2015

Analytic investigation of holographic phase transitions influenced by dark matter sector

We analytically study the phase transitions between s-wave holographic insulator/superconductor and metal/superconductor. The problem is solved by the variational method for the Sturm-Liouville eigenvalue problem in the theory with dark matter sector of U(1)-gauge field coupled to the Maxwell field. Additionally in the probe limit we investigate the marginally stable modes of scalar perturbations in the AdS solitonic background, connected with magnetic field in the dark matter sector. We have found that even with dark matter sector the superconducting transition temperature $T_c$ is proportional to charge density $ρ$ in power 1/3. This value seem to be strong coupling modification of the exponent 2/3 known from the Bose - Einstein condensation of charged local pair bosons in narrow band superconductors. The holographic droplet solution is affected by the coupling to the dark matter. Interestingly in the probe limit the critical chemical potential increases with the decreasing coupling to dark matter making the condensation transition harder to appear.

hep-th↗