2001/10/06 by B. Lorenz, Y. Y. Xue, Lorenz, B. +5
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Superconductivity in MgB2 and Alloys #cond-mat.supr-con
paper · pdf · doi:10.48550/arxiv.cond-mat/0110125
Presented at NATO Advanced Research Workshop "New Trends in Superconductivity", Yalta (Ukraine) 16-20 September, 2001
arxiv created 2001/10/06 · arxiv updated 2009/11/30
The normal state and superconducting properties of MgB2 and Mg1-xAlxB2 are discussed based on structural, transport, and high pressure experiments. The positive Seebeck coefficient and its linear temperature dependence for Tc<T<160 K provide evidence that the low-temperature transport in MgB2 is due to hole-like metallic carriers. Structural and transport data show the important role of defects as indicated by the correlation of Tc, the residual resistance ratio, and the microstrain extracted from x-ray spectra. The decrease of Tc with hydrostatic pressure is well explained by the strong-coupling BCS theory. The large scatter of the pressure coefficients of Tc for different MgB2 samples, however, cannot be explained within this theory. We speculate that pressure may increase the defect density, particularly in samples with large initial defect concentration.