Evidence for dominant Pauli paramagnetic effect in the upper critical field of single-crystalline FeTe0.6 Se0.4

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

doi:10.1103/PhysRevB.81.184511

Evidence for dominant Pauli paramagnetic effect in the upper critical field of single-crystalline FeTe_0.6 Se_0.4

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

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Abstract

We investigated the temperature dependence of the upper critical fields Hc2 (T) of a superconducting FeTe_0.6 Se_0.4 single crystal by measuring its resistivity in static magnetic fields up to 45 T. Our observations of strong bending in the H_c2^ab (T) curves and a nearly isotropic H_c2^ab (0) ≈ H_c2^c (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 _c2^ab (T) and H_c2^c (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.

Original language	English
Article number	184511
Journal	Physical Review B - Condensed Matter and Materials Physics
Volume	81
Issue number	18
DOIs	https://doi.org/10.1103/PhysRevB.81.184511
Publication status	Published - May 14 2010

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics

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abstract = "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.",

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AU - Khim, Seunghyun

AU - Kim, Jae Wook

AU - Choi, Eun Sang

AU - Bang, Yunkyu

AU - Nohara, Minoru

AU - Takagi, Hidenori

AU - Kim, Kee Hoon

PY - 2010/5/14

Y1 - 2010/5/14

N2 - 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.

AB - 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.

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Evidence for dominant Pauli paramagnetic effect in the upper critical field of single-crystalline FeTe_0.6 Se_0.4

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