Multiple Superconducting Gaps, Anisotropic Spin Fluctuations and Spin-Orbit Coupling in Iron-Pnictides

This article reviews the NMR and NQR studies on iron-based high-temperature superconductors by the IOP/Okayama group. It was found that the electron pairs in the superconducting state are in the spin-singlet state with multiple fully-opened energy gaps. The antiferromagnetic spin fluctuations in the normal state are found to be closely correlated with the superconductivity. Also the antiferromagnetic spin fluctuations are anisotropic in the spin space, which is different from the case in copper oxide superconductors. This anisotropy originates from the spin-orbit coupling and is an important reflection of the multiple-bands nature of this new class of superconductors.Comment: 20 pages, 16 figure

Effect of Pulse Frequency and Current Density on Steel Sheet Cleanliness and Hydrogen Permeation

AbstractThe effect of pulse frequency and current density on the effectiveness of biphasic pulse electrocleaning is discussed. Moderate frequency (5Hz) is found to be more effective than lower or higher frequency on steel surface cleanliness. A novel interpretation of cyclic voltammagrams is used to estimate the surface cleanliness. This correlates very well with XPS determination of surface carbon levels. This result is discussed in terms of mechanisms of electrocleaning. Moderate frequency (5–10Hz) is more effective than lower frequency for inhibiting hydrogen permeation. This method can prevent hydrogen brittleness on the electrocleaning high-strength steel