Eur. Phys. J. B (2012) 85: 52
https://doi.org/10.1140/epjb/e2011-20336-2

Regular Article

X-ray diffraction study of spontaneous strain in Fe-pnictide superconductor, NdFeAsO_0.89F_0.11

¹ School of Mathematics and Physics, Kanazawa University, 920-1192 Kanazawa, Japan
² Division of Mathematical and Physical Sciences, Kanazawa University, 920-1192 Kanazawa, Japan
³ School of Health Sciences, Kanazawa University, 920-0942 Kanazawa, Japan
⁴ School of Environmental Design, Kanazawa University, 920-1192 Kanazawa, Japan
⁵ Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, 464-8602 Nagoya, Japan
⁶ JST, TRIP, Nagoya University, Furo-cho, Chikusa-ku, 464-8602 Nagoya, Japan
⁷ Toyota Physical and Chemical Research Institute, Nagakute, 480-1192 Aichi, Japan

^a e-mail: fujishit@staff.kanazawa-u.ac.jp

Received: 2 May 2011
Received in final form: 5 December 2011
Published online: 8 February 2012

Abstract

The lattice parameters of a Nd 1111 Fe-pnictide superconductor, NdFeAsO_0.89F_0.11, were accurately measured using X-ray diffraction between 20 K and 280 K. A very small change in the lattice parameter could be detected in the superconducting phase. This change can be attributed to a spontaneous strain generated in the superconducting phase by the coupling between a superconducting order parameter and the strain. The present results are compared with the thermal expansion coefficients of Ba (Fe_1−xCo_x)₂As₂, in addition to the previous lattice parameter measurements of YBa₂Cu₃O_6.5, MgB₂, La_1.85Sr_0.15CuO₄, and Ba_0.6K_0.4BiO₃.