In the fall of 2001, a group of researchers at Aoyama Gakuin University published a report in Nature on a new superconducting material, MgB2 (magnesium boride), which has a critical temperature of 39 K [1], the finding of which sent shock waves around the world. The discovery of superconductivity in Hg traces back to 1911. Since then, various metals and metal compounds have been confirmed to sh...

Tunneling data on magnesium diboride, MgB2, are reviewed with a particular focus on superconductor–insulator–superconductor (SIS) junctions formed by a break–junction method. The collective tunneling literature reveals two distinct energy scales, a large gap, ∆L ∼ 7.2 meV, close to the expected BCS value, and a small gap, ∆S ∼ 2.4 meV. The SIS break junctions show clearly that the small gap clo...

We present a first principles investigation of the lattice dynamics and electron-phonon coupling of the superconductor MgB2 and the isostructural AlB2 within the framework of density functional perturbation theory using a mixed-basis pseudopotential method. Complete phonon dispersion curves and Eliashberg functions αF are calculated for both systems. We also report on Raman measurements, which ...

Magnesium diboride (MgB2) thin films on r-cut sapphire (r-Al2O3) single crystals were fabricated by a precursor, which was obtained at room temperature via pulsed laser deposition (PLD) method using Nd:YAG laser, and an in situ postannealing process. The onset superconducting transition, Tconset, zero-resistivity Tczero, observed 33.6 31.7 K, respectively, the MgB2 prepared Mg-rich target with ...

We calculate the flux flow resistivity in a superconductor with multiple s-wave superconducting gaps. Our result agrees well with anomalous field dependence of the resistivity recently observed in the two-gap superconductor MgB2.

Stability of 19-filaments MgB2/Ti/Cu/SS wires carrying the transport currents has been examined. Properties of two identical wires annealed at 600 o C/2.5 h and 800 o C/0.5 h were compared. It was found that annealing conditions influence not only the current carrying capacity of MgB2 filaments but also affect the inter-diffusion at Ti/Cu and Cu/SS interfaces, which is worsening the electrical ...

IBA methods were applied to measure elemental depth profiles of precursors and superconducting MgB2 thin films deposited on glassy carbon (Good Fellows) and sapphire (Al2O3) substrates. For each type of substrates we obtained a pair of samples i.e. one amorphous precursor and one superconducting film which were then characterized. A He beam was used to bombard both, precursors and superconducti...

In this study, boron powder with different particle sizes was purified by both chemical and heat treatment methods. The reduction in the size can improve purification no effort on treatment. superconducting properties of drastically changed even only a partial elimination oxygen. On one hand, less oxygen content resulted high Tc Jc values under low magnetic field, most importantly, significant ...

We investigate the physics of the microwave response in YBa2Cu3O7−δ, SmBa2Cu3O7−δ and MgB2 in the vortex state. We first recall the theoretical basics of vortex-state microwave response in the London limit. We then present a wide set of measurements of the field, temperature, and frequency dependences of the vortex state microwave complex resistivity in superconducting thin films, measured by a...

To reduce the usage of liquid helium in MRI magnets, magnesium diboride (MgB2), a high temperature superconductor, has been considered for use in a design of conduction cooled MRI magnets. Compared to NbTi wires the normal zone propagation velocity (NZPV) in MgB2 is much slower leading to a higher temperature rise and the necessity of active quench protection. The temperature rise, resistive vo...