Anisotropic superconducting properties of the aligned Sm0.95La0.05FeAsO0.85F0.15 microcrystalline powderB. C. Chang1, C. H. Hsu1, Y. Y. Hsu2, Z. Wei3, K. Q. Ruan3, X. G. Li3 and H. C. Ku1
1 Department of Physics, National Tsing Hua University - Hsinchu 30013, Taiwan
2 Department of Physics, National Taiwan Normal University - Taipei 11677, Taiwan
3 Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China - Hefei 230026, China
received 15 August 2008; accepted in final form 18 November 2008; published December 2008
published online 12 January 2009
The Sm0.95La0.05FeAsO0.85F0.15 compound is an anisotropic superconductor with a superconducting transition temperature Tc = 52 K. Due to the Fe spin-orbital related anisotropic exchange coupling, the tetragonal microcrystalline powder can be aligned at room temperature using the field-rotation method where the tetragonal ab-plane is parallel to the aligned magnetic field Ba and c-axis along the rotation axis. Anisotropic superconducting properties with anisotropic diamagnetic ratio ~ 2.4 was observed from low-field susceptibility and magnetization M(Ba). The anisotropic low-field phase diagram with the variation of lower critical field gives a zero-temperature penetration depth = 521 nm and = 172 nm. The superconducting anisotropy parameter of 3.0 was obtained for this aligned microcrystalline powder.
74.70.-b - Superconducting materials.
75.30.Fv - Spin-density waves.
75.30.Gw - Magnetic anisotropy.
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