Related papers: Quantum fluctuations and the c-axis optical conduc…
In a two-band superconductor, two qualitatively different fluctuation modes related to the gap modules contribute to free energy and heat capacity, in addition to the phase fluctuations. The first mode has divergent temperature behaviour…
In conventional superconductors, the most direct evidence of the mechanism responsible for superconductivity comes from tunneling experiments in which a clear image of the electron-phonon interaction is revealed. The observed structure in…
In superconductors where the coherence length is comparable to the Fermi wavelength, the electronic levels within a vortex core are quantized, and separated by energies of the order of the superconducting gap. The absence of a continuum…
Recent reflectivity measurements provide evidence for a "violation" of the in-plane optical integral in the underdoped high-T_c compound Bi_2Sr_2CaCu_2O_{8+\delta} up to frequencies much higher than expected by standard BCS theory. The sum…
The c-axis quasiparticle conductivity shows different behavior depending on the nature of the interlayer coupling. For coherent coupling with a constant hopping amplitude $t_{\perp}$, the conductivity at zero frequency and zero temperature…
We present ellipsometric measurements of the far-infrared dielectric response of polycrystalline samples of the new pnictide superconductor RO0.82F0.18FeAs (R=Nd and Sm). We find evidence that the electronic properties are strongly…
A novel phenomenological approach to the analysis of the conductivities of incoherent layered crystals is presented. It is based on the fundamental relationship between the resistive anisotropy $\sigma_{ab}/\sigma_c$ and the ratio of the…
We propose a simple model which explains experimental behavior of $c$-axis resistivity in layered High-T$_c$ superconductors at high fields in a limited temperature range. It is generally accepted that the in-plane dissipation at low…
To shed light on the mechanism responsible for the in-plane resistivity anisotropy in the nematic phase of the iron-based superconductors, we investigate the impact of spin fluctuations on the anisotropic AC conductivity. On the one hand,…
We calculate the c-axis infrared conductivity $\sigma_c(\omega)$ in underdoped cuprate superconductors for spinfluctuation exchange scattering within the CuO$_2$-planes including a phenomenological d-wave pseudogap of amplitude $E_g$. For…
An interesting concept in condensed matter physics is Planckian dissipation, in particular its manifestation in a remarkable phenomenology of superfluid density as a function of superconducting transition temperature. The concept was…
We propose a model and derive analytical expressions for conductivity in heterogeneous fully anisotropic conductors with ellipsoid superconducting inclusions. This model and calculations are useful to analyze the observed temperature…
In multi-band metals quasi-particles arising from different atomic orbitals coexist at a common Fermi surface. Superconductivity in these materials may appear due to interactions within a band (intra-band) or among the distinct metallic…
Recently, superconductivity has been observed in twisted WSe$_2$ moir\'{e} structures (Xia et al., Nature 2024; Guo et al., Nature 2025). Its transition temperature is high, reaching a few percent of the Fermi temperature scale. Here, we…
Several experimental studies have shown the presence of spatially inhomogeneous phase coexistence of superconducting and non superconducting domains in low dimensional organic superconductors. The superconducting properties of these systems…
The interplay between electron-electron interactions and weak localization (or anti-localization) phenomena in two-dimensional systems can significantly enhance the superconducting transition temperature. We develop the theory of quantum…
In cuprate superconductors, tunneling between planes makes possible three-dimensional coherent transport. However, the interlayer tunnelling amplitude is reduced when an order-parameter phase gradient between planes is established. As such,…
The origin of the exceptionally strong superconductivity of cuprates remains a subject of debate after more than two decades of investigation. Here we follow a new lead: The onset temperature for superconductivity scales with the strength…
We show that above the critical temperature of superconductor - metal phase transitions, both the longitudinal and Hall conductivity exhibit strong temperature dependent mesoscopic fluctuations, with amplitudes much larger than the…
We show that the resistive anisotropy of an anisotropic medium is determined by the ratio of the phase coherence lengths. In layered crystals in which the interlayer transport is incoherent, the out-of-plane phase coherence length is fixed…