Seebeck coefficient in correlated low-dimensional organic metals

Abstract

We study the influence of inelastic electron-electron scattering on the temperature variation of the Seebeck coefficient in the normal phase of quasi-one-dimensional organic superconductors. The theory is based on the numerical solution of the semi-classical Boltzmann equation for which the collision integral equation is solved with the aid of the electronic umklapp scattering vertex calculated by the renormalization group method. We show that the one-loop renormalization group flow of momentum and temperature dependent umklapp scattering, in the presence of nesting alterations of the Fermi surface, introduce electron-hole asymmetry in the energy dependence of the anisotropic scattering time. This is responsible for the enhancement of the Seebeck coefficient with respect to the band T -linear prediction and even its sign reversal around the quantum critical point of the phase diagram, namely where the interplay between antiferromagnetism and superconductivity along with the strength of spin fluctuations are the strongest. Comparison of the results with available data on low dimensional organic superconductors is presented and critically discussed.

Superconducting and density-wave instabilities of low-dimensional conductors with a Zeeman coupling to a magnetic field

“…The antinesting amplitude t b of the spectrum will be kept small compared to t b and will serve as a tuning parameter to mimic the effect of pressure. As for interactions, although it exists a large range of possible values able to generate a zero field phase diagram compatible with observations for the Bechgaard salts, we can follow the arguments of earlier works to obtain a reasonable set of figures for the intrachain couplings 20,[43][44][45][46] . For instance, the bare intrachain backscattering amplitude can be fixed to g 1,α 0.32, consistently with the range of values extracted from the enhancement of uniform susceptibility measurements 50 .…”

“…Umklapp scattering is a key scattering ingredient in systems like the Bechggard salts which presents some half-filling band character. It is also essential in the quantum criticality associated with the sequence of SDW-SCd instabilities found in these materials 6,8,[42][43][44][45][46] . The instability of SCd against the formation of dFFLO state is confirmed under field, together with its strength correlated to the distance to the quantum critical point along the antinesting axis or the strength of interactions.…”

Seebeck effect in a thermal QCD medium in the presence of strong magnetic field

“…Thermoelectric properties have been an extensive area of investigation in the field of condensed matter physics over the past three decades. Some of the notable works include the study of the Seebeck effect in superconductors [27][28][29][30][31], Seebeck effect in the graphene superconductor junction [32], electric and thermoelectric transport properties of correlated quantum dots coupled to superconducting electrode [33], transport coefficients of high temperature cuprates [34], thermoelectric properties of a ferromagnetsuperconductor hybrid junction [35], Seebeck coefficient in low dimensional correlated organic metals [36], etc.…”

Seebeck coefficient in low-dimensional fluctuating charge density wave systems

“…Although examined with less sustained attention, the thermopower or the Seebeck coefficient (SC) to which this work is devoted, is another transport observable known to be influenced by fluctuations. When coupled to electron degrees of freedom, fluctuations can introduce significant corrections to the free electron gas -linear in temperature T -prediction of the SC [6][7][8][9][10][11][12][13] . According to the well known Mott SC formula 14,15 , one difficulty with this quantity is that it is influenced by both thermodynamics and effects linked to the energetic of collisions along the Fermi surface 14,16 .…”

“…In the case of the single band repulsive Hubbard model in two dimensions, for instance, the combination of linearized Boltzmann theory and the renormalization group method has made it possible to calculate the electron-electron umklapp scattering time, which contributes distinctively from thermodynamics to the deviations from a linear-T SC 9,10 , as they can be found in cuprates and pnictides as a function of doping 18,19 . The same combination of techniques has been used to calculate the impact of enhanced umklapp scattering by antiferromagnetic fluctuations on the SC of quasi-onedimensional organic metals near a quantum critical point that connects a spin-density wave state to superconductivity under pressure 13 .…”