Magnetic field sweep rate influence on the critical current capabilities of a Fe(Se,Te) crystal

Abstract

The relaxation phenomena of a FeSe0.5Te0.5 single crystal sample, with twinned morphology, exhibiting a second magnetization peak effect have been analyzed by means of dc magnetization measurements as a function of magnetic field (H). Using different magnetic field sweep rates for performing the superconducting hysteresis loops m(H), a change in the width of these curves has been observed together with a shift of the second peak field position. A consequent and significant variation of critical current density Jc has been extracted from the superconducting m(H) curves within the Bean critical state model. In this framework, the ratio between the critical current densities Jc calculated at 200 Oe/s and 5 Oe/s has been calculated showing interesting results in terms of transport capabilities. From the Jc(H) curves at T = 10 K for different sweep rates, the irreversibility field has been obtained for T = 10 K and fitted with a power law. The increasing trend of the irreversibility field as a function of sweep rate could suggest the use of this material for power applications where overheating due to vortices movement inside the superconductor has to be limited.