Related papers: Spin resonance peak in Fe-based superconductors wi…
The interplay of nontrivial topology and superconductivity in condensed matter physics gives rise to exotic phenomena. However, materials are extremely rare where it is possible to explore the full details of the superconducting pairing.…
The resonance, a collective boson mode, was usually thought to be a possible glue of superconductivity. We argue that it is rather a natural product of the \emph{d}-wave pairing and the Fermi surface topology. A universal scaling…
In the new van der Waals Kondo-lattice Fe$_3$GeTe$_2$, itinerant ferromagnetism and heavy fermionic behaviour coexist. Both the key properties of such a system namely a spin-polarized Fermi surface and a low Fermi momentum are expected to…
Prompted by the recent discovery of high-temperature superconductivity in La$_3$Ni$_2$O$_7$ under pressure, this study delves into a theoretical investigation of spin excitations within this intriguing material. Through self-consistent…
We propose that the odd-frequency $s$ wave ($s^{\rm{odd}}$ wave) superconducting gap function, which is usually unstable in the bulk, naturally emerges at the edge of $d$ wave superconductors. This prediction is based on the surface spin…
We present a detailed description of two-band quasi-2D metals with s-wave superconducting (SC) and antiferromagnetic spin-density wave (SDW) correlations. We present a general approach and use it to investigate the influence of the…
The mean field study of bands and the Fermi surfaces (FS's) are carried out for 3-band model of ruthenate. In particular, the lowest spiral state with incommensurate vector Q=2\pi(1/3,1/3) corresponding to nesting of bands display a set of…
Using the fluctuation exchange approximation and a three-orbital model, we study the band renormalization, Fermi surface reconstruction and the superconducting pairing symmetry in the newly-discovered iron-based superconductors. We find…
We report a comprehensive neutron scattering study on the spin excitations in the magnetic Weyl semimetal Co$_3$Sn$_2$S$_2$ with quasi-two-dimensional structure. Both in-plane and out-of-plane dispersions of the spin waves are revealed in…
The superconducting gap is a pivotal character for a superconductor. While the cuprates and conventional phonon-mediated superconductors are characterized by distinct d-wave and s-wave pairing symmetry with nodal and nodeless gap…
Recent observation of a resonance spin excitation at (1/2,1/2,1/2) in the superconducting state of CeCoIn_5 [C. Stock et al., Phys. Rev. Lett. {\bf 100} 087001 (2008)] was interpreted as an evidence for d_{x^2-y^2} gap symmetry, by analogy…
I review theoretical ideas and implications of experiments for the gap structure and symmetry of the Fe-based superconductors. Unlike any other class of unconventional superconductors, one has in these systems the possibility to tune the…
Spin fluctuations are considered to be one of the candidates that drive a sign-reversed s^{\pm} superconducting state in the iron pnictides. In the magnetic scenario, whether the spin fluctuation spectrum exhibits certain unique fine…
We study the spin dynamics of the Resonant Excitonic State (RES) proposed, within the theory of an emergent SU(2) symmetry, to explain some properties of the pseudo-gap phase of cuprate superconductors. The RES can be described as a…
The interference between spin-density-wave and superconducting instabilities in quasi-one-dimensional correlated metals is analyzed using the renormalization group method. At the one-loop level, we show how the interference leads to a…
Hidden spin-density waves (hSDW) with Neel ordering vector (pi,pi) have been proposed recently as parent groundstates to electron-doped iron-selenide superconductors. Doping such groundstates can result in visible electron-type Fermi…
The neutron spin resonance is a collective magnetic excitation that appears in copper oxide, iron pnictide, and heavy fermion unconventional superconductors. Although the resonance is commonly associated with a spin-exciton due to the…
A single-channel quantum wire with two well-separated Zeeman subbands and in the presence of a weak spin-orbit coupling is considered. An impurity level which is split off the upper subband is degenerate with the continuum of the lower…
Unconventional superconductivity in iron pnictides and chalcogenides has been suggested to be controlled by the interplay of low-energy antiferromagnetic spin fluctuations and the particular topology of the Fermi surface in these materials.…
We consider the possibility of formation of an unconventional spin density wave (USDW) in quasi-one dimensional electronic systems. In analogy with unconventional superconductivity, we develop a mean field theory of SDW allowing for the…