Compressed HS: inter-sublattice Coulomb coupling in a high-T superconductor.

Upon thermal annealing at or above room temperature (RT) and at high hydrostatic pressure P ~ 155 GPa, sulfur trihydride HS exhibits a measured maximum superconducting transition temperature T ~ 200 K. Various theoretical frameworks incorporating strong electron-phonon coupling and Coulomb repulsion have reproduced this record-level T . Of particular relevance is that experimentally observed H-D isotopic correlations among T , P, and annealed order indicate an H-D isotope effect exponent α limited to values  ⩽  0.

High-T superconductivity in CsC compounds governed by local Cs-C Coulomb interactions.

Unique among alkali-doped A C fullerene compounds, the A15 and fcc forms of CsC exhibit superconducting states varying under hydrostatic pressure with highest transition temperatures at [Formula: see text]  =  38.3 and 35.2 K, respectively.

The superconducting transition temperatures of Fe(1+x)Se(1-y), Fe(1+x)Se(1-y)Te(y) and (K/Rb/Cs)(z)Fe(2-x)Se2.

In a recent contribution to this journal, it was shown that the transition temperatures of optimal high-T(C) compounds obey the algebraic relation T(C0) = k(-1)(B)/ℓζ, where ℓ is related to the mean spacing between interacting charges in the layers, ζ is the distance between interacting electronic layers, β is a universal constant and k(B) is Boltzmann's constant. The equation was derived assuming pairing based on interlayer Coulomb interactions between physically separated charges. This theory was initially validated for 31 compounds from five different high-T(C) families (within an accuracy of ±1.

Concerning the superconducting gap symmetry in YBa₂Cu₃O₇- δ, YBa₂Cu₄O, and La₂ - xSrxCuO₄ determined from muon spin rotation in mixed states of crystals and powders.

Muon spin rotation (μ(+)SR) measurements of square-root second moments of local magnetic fields σ in superconducting mixed states, as published for oriented crystals and powder samples of YBa(2)Cu(3)O(7 - δ) (δ≈0.05), YBa(2)Cu(4)O(8) and La(2 - x)Sr(x)CuO(4) (x ∼ 0.15-0.

Electrical Resistivity and Stoichiometry of CaxC60 and SrxC60 Films.

The temperature- and concentration-dependent resistivities of annealed CaxC(60) and SrxC(60) films were measured near room temperature. Resistivity minima were observed at x = 2 and 5. The resistivities of these films were rho(min) approximately 1 ohm-centimeter for x = 2 and rho(min) approximately 10(-2) ohm-centimeter for x = 5.

Electrical resistivity and stoichiometry of kkhgr c60 films.

Electrical resistances of polycrystalline fullerene (C(60)) films were monitored while the films were being doped in ultrahigh vacuum with potassium from a molecular-beam effusion source. Temperature- and concentration-dependent resistivities of K(chi) C(60) films in equilibrium near room temperature were measured. The resistance changes smoothly from metallic at chi approximately 3 to activated as chi --> = 0 or chi --> 6.