Critical current density and pinning behaviour of mono-core MgB2 wires prepared by internal magnesium diffusion and in-situ powder-in-tube method

• MgB2 wires produced by internal Mg diffusion and powder-in-tube method are analyzed.
• Properties of the wires are investigated by magnetic and transport measurement.
• Dominant difference between the wires is in critical current density.
• Mg diffusion wire has up to 50 times higher Jc than powder-in-tube wire.

Mono-core MgB2 wires were produced by internal magnesium diffusion (IMD) and in-situ powder-in-tube (PIT) technique. Hysteresis loops and magnetic relaxations were measured to calculate critical current density, Jcm (via Bean’s critical state model) and mean effective activation energy (via Anderson’s flux creep theory). To calculate Jcm of the IMD sample, the formulae for typical cylindrical sample geometry must have been modified properly with regard to IMD hollow cylinder geometry. Results for Jcm were compared to direct transport measurements. Also studied was the irreversibility field, Birr, and upper critical field, Bc2. It was found that the dominant difference between wires is in Jc. For the IMD sample, Jc was higher and less field-dependent than Jc of the PIT sample.