Transport properties and high upper critical field of a Fe(Se,Te) iron based superconductor

A Fe(Se,Te) iron based crystal has been studied using dc magnetic measurements as a function of temperature ( T ) and magnetic field ( H ). Firstly, the field dependence of the critical current density J c has been extracted from the superconducting hysteresis loops m ( H ) at different temperatures within the Bean critical state model in order to obtain information about the transport properties of the sample. The knowledge of the critical current density values as a function of the field for temperatures near T c allow us to determine the values and the behavior of the irreversibility field H irr as a function of the temperature. On the other hand, by means of zero field cooling m ( T ) measurements at different magnetic fields, the upper critical field H c2 has been evaluated as a function of the temperature. Both irreversibility field and upper critical field have been fitted by the equation H ( T ) = H (0)(1 − T / T * ) n allowing us to obtain the values of the related parameters which are in good agreement with those found in literature for the IBS systems.