non-Fermi Liquid Corrections Research Articles

Thermal effects in non-Fermi liquid superconductivity

We revisit the interplay between superconductivity and quantum criticality when thermal effects from virtual static bosons are included. These contributions, which arise from an effective theory compactified on the thermal circle, strongly affect field-theoretic predictions even at small temperatures. We argue that they are ubiquitous in a wide variety of models of non-Fermi liquid behavior, and generically produce a parametric suppression of superconducting instabilities. We apply these ideas to non-Fermi liquids in $d=2$ space dimensions, obtained by coupling a Fermi surface to a Landau-damped soft boson. Extending previous methods developed for $d=3-\epsilon$ dimensions, we determine the dynamics and phase diagram. It features a naked quantum critical point, separated by a continuous infinite order transition from a superconducting phase with strong non-Fermi liquid corrections. We also highlight the relevance of these effects for (numerical) experiments on non-Fermi liquids.

Type-I and type-II Weyl fermions, topological depletion, and universal subleading scaling across topological phase transitions

It remains an open problem if there are universal scaling functions across a topological quantum phase transition (TPT) without an order parameter, but with extended Fermi surfaces (FS ). Here, we study a simple system of fermions hopping in a cubic lattice subject to a Weyl type spin-orbit coupling (SOC). As one tunes the SOC parameter at the half filling, the system displays Weyl fermions and also various TPT due to the collision of particle-particle or hole-hole Weyl Fermi Surface (WFS). At the zero temperature, the TPT is found to be a third order one whose critical exponent is determined. We derive the scaling functions of the specific heat, compressibility and magnetic susceptibilities. In contrast to all the previous cases in quantum or topological transitions, although the leading terms are non-universal and cutoff dependent, the sub-leading terms satisfy universal scaling relations. The sub-leading scaling leads to the topological depletions (TD) which show non-analytic and non-Fermi liquid corrections in the quantum critical regime, can be easily distinguished from the analytic leading terms and detected experimentally. One can also form a topological Wilson ratio from the TD of two conserved quantities such as the specific heat and the compressibility. As a byproduct, we also find Type II Weyl fermions appearing as the TPT due to the collision of the extended particle-hole WFS. Experimental realizations and detections in cold atom systems and materials with SOC are discussed.

Cooling of neutron star including magnetic interaction

In this work we calculate the neutrino mean free path (MFP) and neutrino emissivity with non-Fermi liquid (NFL) corrections of degenerate quark matter. Subsequently the role of these NFL corrections on the cooling of neutron star has been demonstrated. The cooling curve shows moderate enhancement due to this NFL corrections.

Role of magnetic interactions in neutron stars

In this work, we present a calculation of the non-Fermi liquid correction to the specific heat of magnetized degenerate quark matter present at the core of the neutron star. The role of non-Fermi liquid corrections to the neutrino emissivity has been calculated beyond leading order. We extend our result to the evaluation of the pulsar kick velocity and cooling of the star due to such anomalous corrections and present a comparison with the simple Fermi liquid case.

Role of magnetic interactions in neutron stars

In this work, we present a calculation of the non-Fermi liquid correction to the specific heat of magnetized degenerate quark matter present at the core of the neutron star. The role of non-Fermi liquid corrections to the neutrino emissivity has been calculated beyond leading order. We extend our result to the evaluation of the pulsar kick velocity and cooling of the star due to such anomalous corrections and present a comparison with the simple Fermi liquid case.

Modifications to the pulsar kick velocity due to magnetic interactions in dense plasma

In this work we calculate the pulsar kick velocity of a magnetized neutron star (NS) composed of a degenerate quark matter core with non-Fermi liquid (NFL) correction. Both the leading order (LO) and next to LO (NLO) corrections to the kick velocity have been incorporated. In addition, the NFL corrections to the specific heat of magnetized quark matter have been presented. This has been taken into account to calculate the kick velocity of the NS. The results show a significant departure from the normal Fermi liquid estimates. The relation between radius and temperature has been shown with a kick velocity of 100 km s−1 with and without NFL corrections.

Non-Fermi liquid behavior of thermal relaxation time in degenerate electron plasma

The thermal relaxation time (${\ensuremath{\tau}}_{{\ensuremath{\kappa}}_{\mathrm{ee}}}$) for the degenerate electron plasma has been calculated by incorporating non-Fermi liquid corrections both for the thermal conductivity and specific heat capacity. Perturbative results are presented by making expansion in $T/{m}_{D}$ with next to leading order corrections. We see that the next to leading order non-Fermi liquid corrections further reduce the decrease in relaxation time due to the leading order corrections.

Non-Fermi liquid corrections to the neutrino mean free path in dense quark matter

We calculate the neutrino mean free path with non-Fermi liquid corrections in quark matter from scattering and absorption processes for both degenerate and nondegenerate neutrinos. We show that the mean free path decreases due to the non-Fermi liquid corrections, leading to ${l}_{\mathrm{mean}}^{\ensuremath{-}1}\ensuremath{\sim}[\dots{}+\dots{}{C}_{F}^{2}{\ensuremath{\alpha}}_{s}^{2}\mathrm{ln}({m}_{D}/T{)}^{2}]$. This reduction results in a higher rate of scattering.

Specific heat of normal, degenerate quark matter: Non-Fermi liquid corrections

In normal degenerate quark matter, the exchange of dynamically screened transverse gluons introduces infrared divergences in the quark self-energies that lead to the breakdown of the Fermi liquid description. If the cores of neutron stars are composed of quark matter with a normal component, cooling by direct quark URCA processes may be modified by non-Fermi liquid corrections. We find that while the quasiparticle density of states is finite and nonzero at the Fermi surface, its frequency derivative diverges and results in non-Fermi liquid corrections to the specific heat of the normal, degenerate component of quark matter. We study these non-perturbative non-Fermi liquid corrections to the specific heat and the temperature dependence of the chemical potential and show that these lead to a reduction of the specific heat.

Non-Fermi liquid correction to uniform spin susceptibility of singlet band below Tc

A new expression for the uniform static spin susceptibility below T c in singlet band model has been deduced. The formula takes into account strong electron correlation effects. The comparison of the theoretical curve with experimental data yields another value of 2Δ k BT c than in the case of the usual Fermi liquid. In particular, for YBa 2Cu 3O 7 the extracted ratio 2Δ k BT c = 4.87 and can be interpreted in favor of the superexchange pairing mechanism.

Corrections to Fermi-liquid theory of correlated metals

Quasiparticle excitations of Landau-Fermi liquids can be described by a Boltzmann-Landau transport equation. We use this property to characterize the Fermi-liquid state of correlated metals, and discuss leading corrections to standard results of Fermi-liquid theory. Our non-Fermi liquid corrections are smaller than the standard results by a factor small(D−1), where D is the dimension of the metal and small represents the expansion parameters of Fermi-liquid theory. We present, as an instructive example, results for the first-order non-Fermi liquid corrections to Korringa's law.