Friedel-Like Oscillations from Interstitial Iron in Superconducting ${\mathrm{Fe}}_{1+y}{\mathrm{Te}}_{0.62}{\mathrm{Se}}_{0.38}$

Friedel-Like Oscillations from Interstitial Iron in Superconducting ${Fe}_{1 + y} {Te}_{0.62} {Se}_{0.38}$

V. Thampy, J. Kang, J. A. Rodriguez-Rivera, W. Bao, A. T. Savici, J. Hu, T. J. Liu, B. Qian, D. Fobes, Z. Q. Mao, C. B. Fu, W. C. Chen, Q. Ye, R. W. Erwin, T. R. Gentile, Z. Tesanovic, and C. Broholm

Phys. Rev. Lett. 108, 107002 – Published 7 March 2012

Abstract

Using polarized and unpolarized neutron scattering, we show that interstitial Fe in superconducting ${Fe}_{1 + y} {Te}_{1 - x} {Se}_{x}$ induces a magnetic Friedel-like oscillation that diffracts at $Q_{⊥} = (\frac{1}{2} 0)$ and involves $> 50$ neighboring Fe sites. The interstitial $> 2 μ_{B}$ moment is surrounded by compensating ferromagnetic four-spin clusters that may seed double stripe ordering in ${Fe}_{1 + y} Te$ . A semimetallic five-band model with $(\frac{1}{2} \frac{1}{2})$ Fermi surface nesting and fourfold symmetric superexchange between interstitial Fe and two in-plane nearest neighbors largely accounts for the observed diffraction.

Received 23 September 2011

DOI:https://doi.org/10.1103/PhysRevLett.108.107002

Authors & Affiliations

V. Thampy¹, J. Kang¹, J. A. Rodriguez-Rivera^2,3, W. Bao⁴, A. T. Savici⁵, J. Hu⁶, T. J. Liu⁶, B. Qian⁶, D. Fobes⁶, Z. Q. Mao⁶, C. B. Fu^7,8,9, W. C. Chen^3,9, Q. Ye⁵, R. W. Erwin², T. R. Gentile⁹, Z. Tesanovic¹, and C. Broholm^1,2

¹Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
²NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
³Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20740, USA
⁴Department of Physics, Renmin University of China, Beijing 100872, China
⁵NSSD, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
⁶Department of Physics, Tulane University, New Orleans, Louisiana 70118, USA
⁷Department of Physics, Indiana University, Bloomington, Indiana 47408, USA
⁸Department of Physics, Shanghai Jiaotong University, Shanghai, 200240, China
⁹National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA