Spin reorientation transition in Na-doped BaFeb>2b>Asb>2b> studied by single-crystal neutron diffraction

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• 作者：Florian Waß ; er ; Sabine Wurmehl ; Saicharan Aswartham ; Yvan Sidis ; J. T. Park ; Astrid Schneidewind ; Bernd B&uuml ; chner and Markus Braden
• 刊名：physica status solidi (b)
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：254
• 期：1
• 全文大小：1767K
• ISSN：1521-3951

文摘

Several hole-doped BaFeb>2b>Asb>2b> compounds were recently shown to exhibit a second magnetic phase transition in the concentration range close to the full suppression of antiferromagnetic (AFM) order. At this additional transition ordered magnetic moments reorient from in-plane to out-of-plane alignment associated with a suppression of the orthorhombic distortion. We have studied the magnetic properties of such a representative hole-doped system, Bab>1–xb>Nab>xb>Feb>2b>Asb>2b> with 0.25 ≤ x ≤ 0.40, by neutron diffraction on large single crystals. With increasing Na substitution (0.25 ≤ x ≤ 0.39) the AFM transition temperature sharply decreases, while the spin-reorientation transition temperature is rather constant, until both magnetic phases are completely suppressed at x = 0.40. For all studied Na concentrations the additional transition is related to the spin reorientation, which, however, is complete only in the middle of the concentration range of the out-of-plane phase. In the superconducting state, the intensities of magnetic Bragg reflections become heavily suppressed; this effect seems to increase for larger Tb>cb> and reaches ∼50% in Bab>0.61b>Nab>0.39b>Feb>2b>Asb>2b>. In samples with coexisting in-plane and out-of-plane ordering, this superconductivity induced suppression of ordered moments is significantly stronger for the out-of-plane components indicating that this phase more strongly competes with superconductivity.