Growth of c-Axis-Oriented Superconducting KFe2As2 Thin Films

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• 作者：Hidenori Hiramatsu ; Shogo Matsuda ; Hikaru Sato ; Toshio Kamiya ; Hideo Hosono
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：August 27, 2014
• 年：2014
• 卷：6
• 期：16
• 页码：14293-14301
• 全文大小：479K
• ISSN：1944-8252

文摘

KFe₂As₂, an iron-based superconductor, is expected to exhibit large spin Hall conductivity, and fabrication of high-quality thin films is requisite for evaluation of this effect and application to spintronics devices. Thin-film growth of KFe₂As₂ is difficult because of two intrinsic properties; its extremely hygroscopic nature and the high vapor pressure of potassium. We solved these issues by combining room-temperature pulsed laser deposition using K-rich KFe₂As₂ targets with thermal crystallization in KFe₂As₂ powder after encapsulation in an evacuated silica-glass tube with all of the processes conducted in a vacuum chamber and a dry Ar atmosphere in a glovebox. The optimized KFe₂As₂ films on (La,Sr)(Al,Ta)O₃ single-crystal substrates were obtained by crystallization at 700 掳C, and they were strongly c-axis oriented. The electrical measurements were performed with thin films protected by grease passivation to block reaction with the atmosphere. The KFe₂As₂ films exhibited a superconductivity transition at 3.7 K.

Keywords:

iron-based superconductors; air-sensitive materials; potassium; thin films; pulsed laser deposition; thermal annealing