Role of c halcogen vapor annealing in inducing bulk s uperc onductivity in Fe_{1+ y}Te_{1− x}Se_x

Wenzhi Lin¹, P. Ganesh¹, Anthony Gianfrancesco², Jun Wang¹, Tom Berlijn^1,3, Thomas A. Maier^1,3,Sergei V. Kalinin¹, Brian C. Sales⁴, and Minghu Pan^5,*

• ¹Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
• ²UT/ORNL Bredesen Center, University of Tennessee, Knoxville, Tennessee 37996, USA
• ³Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
• ⁴Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
• ⁵School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
• ^*Author to whom correspondence should be addressed: mhupan@gmail.com
•       Recent investigations have shown that Fe1+yTe1−xSex can be made superconducting by annealing it in Se and O vapors. The current lore is that these chalcogen vapors induce superconductivity by removing the magnetic excess Fe atoms. To investigate this phenomenon, we performed a combination of magnetic susceptibility, specific heat, and transport measurements together with scanning tunneling microscopy and spectroscopy and density functional theory calculations on Fe1+yTe1−xSex treated with Te vapor. We conclude that the main role of the Te vapor is to quench the magnetic moments of the excess Fe atoms by forming FeTem (m≥1) complexes. We show that the remaining FeTem complexes are still damaging to the superconductivity and therefore that their removal potentially could further improve superconductive properties in these compounds. 

• Phys. Rev. B  91, 060513(R) – Published 27 February 2015

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