Magnetic relaxation in MgB2 monofilamentary tapes

To study the flux creep in MgB2 monofilamentary tapes embedded in nickel alloy matrix, we have measured the magnetic relaxation M(t) in the temperature range from 4.2 K up to 30 K applying an external magnetic field of 10 kOe both parallel and perpendicular to the filament direction. We have analyzed the experimental curves including the first seconds of the magnetic relaxations. In this work, we discuss the dependence of the M(t) creep rate and the effective pinning energy on the temperature in presence of an applied magnetic field, taking also in account the sample geometry.