Low temperature Pmmm and C2/m phases in Sr2CuO3+δ high temperature superconductor
Wang Hai-Bo1, Luo Zhen-Lin2, ‡, Yang Yuan-Jun2, Liu Qing-Qing3, Hu Si-Xia2, Yang Meng-Meng2, Jin Chang-Qing3, Gao Chen2, 4, †
       

(a) Temperature dependence of Debye–Waller factor of Cu–O coordination in Sr2CuO3+δ, showing anomalous change around 115 K and 60 K. The circles in the Fig. 4(a) are the fitting result using Debye model. (b) Temperature evolution of the peak intensity ratio R = ( b 1 − a 1 ) / ( a 1 + b 1 ) obtained from the XANES spectra of Sr2CuO3+δ, also showing clear changes around 115 K and 60 K. The inset is a typical Cu K-edge XANES of Sr2CuO3+δ (δ = 0.4) at 20 K and its best fitting result.