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تسجيل مستخدم جديدCan antiferromagnetism and superconductivity coexist in the high-field paramagnetic superconductor Nd(O,F)FeAs?
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We present measurements of the temperature and field dependencies of the magnetization M(T,H) of Nd(O0.89F0.11)FeAs at fields up to 33T, which show that superconductivity with the critical temperature Tc ~ 51K cannot coexist with antiferromagnetic ordering. Although M(T,H) at 55 < T < 140K exhibits a clear Curie-Weiss temperature dependence corresponding to the Neel temperature TN ~ 11-12K, the behavior of M(T,H) below Tc is only consistent with either paramagnetism of weakly interacting magnetic moments or a spin glass state. We suggest that the anomalous magnetic behavior of an unusual high-field paramagnetic superconductor Nd(O1-xFx)FeAs is mostly determined by the magnetic Nd ions.
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_B$, on the border with the Mott insulating state. We fit the bands crossing the Fermi surface, derived from Fe and As, to a tight-binding Hamiltonian using maximally localized Wannier functions on Fe 3d and As 4p orbitals. The model Hamiltonian accurately describes the Fermi surface obtained via first-principles calculations. Due to the evident proximity of superconductivity to antiferromagnetism and the Mott transition, we suggest that the system may be an analog of the electron doped cuprates, where antiferromagnetism and superconductivity coexist.
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