A generalized form of Ginzburg–Landau theory is proposed which explains the non-hexagonal flux-line lattice found both in metallic and magnetic superconductors without invoking any anisotropic material-dependent properties. The Gibbs energy density postulated for magnetic superconductors (g) is of the form g(B, T ) = α|ψ |2 + 1 2β|ψ |4 + [1/(2m)]|(−ih̄∇−2eA)ψ |2 + ∫ (B/μ0 − Mions) · dB − (B/μ0 −...

One of the common features of unconventional superconducting systems such as the heavy-fermion, high transition-temperature cuprate and iron-pnictide superconductors is that the superconductivity emerges in the vicinity of long-range antiferromagnetically ordered state. In addition to doping charge carriers, the application of external pressure is an effective and clean approach to induce uncon...

We study the coexistent state of the spin density wave (SDW) and the charge density wave (CDW) in a one-dimensional extended Hubbard model. We find that the coexistent state of SDW and CDW is stabilized in various electron-filling cases when band parameters are for organic conductors. The ground state energies have cusp-like minima at n/4m-fillings, where n and m are integers. The maxima of the...

Recent experimental advances in atomically thin transition metal dichalcogenide (TMD) metals have unveiled a range of interesting phenomena including the coexistence of charge-density-wave (CDW) order and superconductivity down to the monolayer limit. The atomic thickness of two-dimensional (2D) TMD metals also opens up the possibility for control of these electronic phase transitions by electr...

Fluctuations around an antiferromagnetic quantum critical point (QCP) are believed to lead to unconventional superconductivity and in some cases to high-temperature superconductivity. However, the exact mechanism by which this occurs remains poorly understood. The iron-pnictide superconductor BaFe2(As(1-x)P(x))2 is perhaps the clearest example to date of a high-temperature quantum critical supe...

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 bands (inter-band). Here we consider the suppression of superconductivity in the intra-band case due to hybridization. The fluctuations at the superconducting q...

High quality c^-axis oriented thin and ultra-thin films have been grown in situ on (100) surfaces of ZrO?, SrTiO, and MgO. Sharp transitions were observed with T,,,,,, of 87-91 K for films thicker than 70 A. On atomically polished MgO substrates films as thin as 15 A revealed a full transition to superconductivity above 45.5 K. The critical current density at 77 K was found to be strongly depen...

– We argue that the pseudogap phase may be an attribute of the non-BCS pairing of quantum-critical, diffusive fermions near the antiferromagnetic quantum critical point. We derive and solve a set of three coupled Eliashberg-type equations for spin-mediated pairing and show that in some T range below the pairing instability, there is no feedback from superconductivity on fermionic excitations, a...

Chiral superconductivity, which breaks time-reversal symmetry, can exhibit a wealth of fascinating properties that are highly sought after for nanoscience applications. We identify doped graphene monolayer as a system where chiral superconductivity can be realized. In this material, a unique situation arises at a doping where the Fermi surface is nested and the density of states is singular. In...