Related papers: Universal approach to light driven "superconductiv…
Based on experimental results and our previous theoretical work, a microscopic theory of high temperature superconductivity is conjectured. In this conjecture, superconducting and antiferromagnetic long-range orders are driven by interlayer…
The optical conductivity of Ba(Fe$_{0.92}$Co$_{0.08}$)$_2$As$_2$ shows a clear signature of the superconducting gap, but a simple $s$-wave description fails in accounting for the low frequency response. This task is achieved by introducing…
Ultrafast electron beams are essential for many applications, yet space-charge interactions in high-intensity beams lead to energy dissipation, coherence loss, and pulse broadening. Existing techniques mitigate these effects by using…
We examine electromagnetically induced transparency (EIT) in an ensemble of cold $\Lambda-$type atoms induced by a quantum control field in multi-mode coherent states and compare it with the transparency created by the classical light of…
The superconducting phase of the 2D one-band Hubbard model is studied within the FLEX approximation and by using an Eliashberg theory. We investigate the doping dependence of $T_c$, of the gap function $\Delta ({\bf k},\omega)$ and of the…
The origin of the high-temperature superconducting state observed in FeSe thin films, whose phase diagram displays no sign of magnetic order, remains a hotly debated topic. Here we investigate whether fluctuations arising due to the…
We investigate the properties of a system where the itinerant electrons coexist and interact with the preformed local pairs. Using the nonperturbative continuous unitary transformation technique we show that Andreev-type scattering between…
Advances in manipulating the structure of optical beams enable the study of interaction between structured light and low-dimensional semiconductor systems. We explore the photocurrents in two-dimensional systems excited by such…
The phenomenon of field-induced superconductor-to-insulator transitions observed experimentally in electron-doped SrTiO$_{3}$/LaAlO$_{3}$ interfaces, analyzed recently by means of 2D superconducting fluctuations theory (Phys. Rev. B…
We present a theory of optical conductivity in systems with finite-momentum Cooper pairs. In contrast to the BCS pairing where AC conductivity is purely imaginary in the clean limit, there is nonzero AC absorption across the superconducting…
We describe the high-temperature superconductor La$_{2-x}$Sr$_x$CuO$_4$ in the underdoped regime in terms of a mixed-phase model, which consists of superconducting clusters embedded in the antiferromagnetic matrix. Our work is motivated by…
Here we report extensive ultrafast time-resolved reflectivity experiments on overdoped Bi$_{2}$Sr$_{2}$Ca$_{1-x}$Y$_x$Cu$_{2}$O$_{8+\delta}$ single crystals (T$_C$=78 K) aimed to clarify the nature of the superconducting-to-normal-state…
The physical pictures of the electron pairing structure and pairing mechanisms in superconductors are reviewed. An initial idea for a new physical picture of the origin and nature of the pairing is proposed. The idea is based on the…
The condensation energy can be shown to be a moment of the change in the occupied part of the spectral function when going from the normal to the superconducting state. As a consequence, there is a one to one correspondence between the…
In most superconductors the transition to the superconducting state is driven by the binding of electrons into Cooper-pairs. The condensation of these pairs into a single, phase coherent, quantum state takes place concomitantly with their…
The paradigmatic Migdal-Eliashberg theory of the electron-phonon problem is central to the understanding of superconductivity in conventional metals. This powerful framework is justified by the smallness of the Debye frequency relative to…
Experiments often show that the photoconductance $\sigma$ of a semiconductor system and the light intensity $I$ are related by $\sigma\sim I^\gamma$. Conventional theories give a satisfactory explanation for $\gamma=1$ or $\gamma=1/2$, but…
In this review we demonstrate that superconducting pairing, mediated by the exchange of spin fluctuations, is a viable alternative to conventional phonon-mediated pairing. We discuss in detail the normal state properties, the spin…
Photoemission and optical experiments indicate that the transition to superconductivity in cuprates is an 'undressing' transition . In photoemission this is seen as a coherent quasiparticle peak emerging from an incoherent background, in…
Recently, the possibility of inducing superconductivity for electrons in two dimensional materials has been proposed via cavity-mediated pairing. The cavity-mediated electron-electron interactions are long range, which has two main effects:…