We investigated the temperature dependence of the upper critical fields Hc2 (T) of a superconducting FeTe0.6 Se0.4 single crystal by measuring its resistivity in static magnetic fields up to 45 T. Our observations of strong bending in the Hc2ab (T) curves and a nearly isotropic Hc2ab (0) ≈ Hc2c (0) ≈ 48 T support the presence of a strong Pauli paramagnetic effect. We show that the Werthamer-Helfand-Hohenberg formula that includes both the Pauli limiting and the spin-orbit scattering can effectively describe both the H c2ab (T) and Hc2c (T) curves. An enhancement in the quasiparticle density of states or the increased scattering resulting from Te(Se) vacancies or excess Fe is discussed as a possible origin for the manifesting Pauli paramagnetic effect.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - May 14 2010|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics