Superconductivity and vortex pinning in Fe1.04Te0.60Se0.40 single crystal
Max-Planck-Institut für Festkörperforschung - Heisenbergstraße 1, D-70569 Stuttgart, Germany, EU
Accepted: 12 November 2010
Measurements of specific heat, resistivity, and magnetic hysteresis loop were performed on high-quality Fe1.04Te0.60Se0.40 single crystal. The exponential decay of the specific heat of the sample can be well described by the BCS-weak coupling theory. The resistive upper critical fields Hc2 were extracted with the zero-resistance criteria. The slopes dHc2ab /dT and dHc2c /dT collected from the existing data in the iron chalcogenide family are roughly scaled by the relation dHc2 /dT∝Tc for both H||c and H||ab configurations, which can be interpreted in terms of a pair-breaking effect. Comparing the AFe2As2 superconductors, the second magnetization peak observed in the magnetic hysteresis loops for H||c is strongly broadened for the Fe1.04Te0.60Se0.40 single crystal. We demonstrate that the δTc pinning associated with spatial fluctuations of the transition temperatures gives rise to the broadening of the second peak.
PACS: 74.70.Xa – Pnictides and chalcogenides / 74.25.Op – Mixed states, critical fields, and surface sheaths / 74.25.Wx – Vortex pinning (includes mechanisms and flux creep)
© EPLA, 2010