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arXiv · 1001.4017

Evidence for dominant Pauli paramagnetic effect in the upper critical fields of a FeTe0.6Se0.4 superconductor

Seunghyun Khim·Jae Wook Kim·Eun Sang Choi·Yunkyu Bang·Minoru Nohara·Hidenori Takagi·Kee Hoon Kim
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Abstract

We investigate temperature-dependence of the upper critical fields Hc2(T) of a superconducting FeTe0.6Se0.4 single crystal by measuring resistivity in static magnetic fields up to 45 T. The observations of strong bending in the Hc2ab(T) curves and nearly isotropic Hc2ab(0) ~ Hc2c(0) ~ 48 T support the presence of strong Pauli paramagnetic effect. We show that the Werthamer-Helfand-Hohenberg formula considering the Pauli limiting and the spin-orbit scattering together can effectively describe both Hc2ab(T) and Hc2c(T) curves. The enhancement in quasi-particle density of states or increased scattering resulting from Te(Se) vacancy or excess Fe is discussed as a possible origin for the manifesting Pauli paramagnetic effect.

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Seunghyun Khim, Jae Wook Kim, Eun Sang Choi, Yunkyu Bang, Minoru Nohara, Hidenori Takagi, Kee Hoon Kim. 2010-01-22. Evidence for dominant Pauli paramagnetic effect in the upper critical fields of a FeTe0.6Se0.4 superconductor. https://doi.org/10.1103/physrevb.81.184511

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