Structural Phase Transitions and Superconductivity in Fe1+δSe0.57Te0.43 at Ambient and Elevated Pressures

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• 作者：Nathalie C. Gresty ; Yasuhiro Takabayashi ; Alexey Y. Ganin ; Martin T. McDonald ; John B. Claridge ; Duong Giap ; Yoshikazu Mizuguchi ; Yoshihiko Takano ; Tomoko Kagayama ; Yasuo Ohishi ; Masaki Takata ; Matthe
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：November 25, 2009
• 年：2009
• 卷：131
• 期：46
• 页码：16944-16952
• 全文大小：505K
• 年卷期：v.131,no.46(November 25, 2009)
• ISSN：1520-5126

文摘

The ternary iron chalcogenide, Fe_1.03Se_0.57Te_0.43 is a member of the recently discovered family of Fe-based superconductors with an ambient pressure T_c of 13.9 K and a simple structure comprising layers of edge-sharing distorted Fe(Se/Te)₄ tetrahedra separated by a van der Waals gap. Here we study the relationship between its structural and electronic responses to the application of pressure. T_c depends sensitively on applied pressure attaining a broad maximum of 23.3 K at 3 GPa. Further compression to 12 GPa leads to a metallic but nonsuperconducting ground state. High-resolution synchrotron X-ray diffraction shows that the superconducting phase is metrically orthorhombic at ambient pressure but pressurization to 3 GPa leads to a structural transformation to a more distorted structure with monoclinic symmetry. The exact coincidence of the crystal symmetry crossover pressure with that at which T_c is maximum reveals an intimate link between crystal and electronic structures of the iron chalcogenide superconductors.