Eur. Phys. J. Special Topics 228, 725–731 (2019)
https://doi.org/10.1140/epjst/e2019-800169-5

Regular Article

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

¹ Department of Physics “E.R. Caianiello”, University of Salerno, via Giovanni Paolo II, 132, Fisciano (Salerno) 84084, Italy
² CNR-SPIN Salerno, via Giovanni Paolo II, 132, Fisciano (Salerno) 84084, Italy
³ Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria

^a e-mail: polimax@sa.infn.it

Received: 4 October 2018
Received in final form: 28 November 2018
Published online: 3 July 2019

Abstract

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.