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arXiv · 1406.3734

Critical Behavior of the SDW Transition in Underdoped Ba(Fe1-xCox)2As2 (x <=0.05): 75As NMR Investigation

F. L. Ning·M. Fu·D. A. Torchetti·T. Imai·A. S. Sefat·P. Cheng·B. Shen·H. -H Wen
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Abstract

We investigate the nature of the SDW (Spin Density Wave) transition in the underdoped regime of an iron-based high Tc superconductor Ba(Fe1-xCox)2As2 by 75As NMR, with primary focus on a composition with x = 0.02 (T_SDW = 99 K).We demonstrate that critical slowing down toward the three dimensional SDW transition sets in at the tetragonal to orthorhombic structural phase transition, Ts = 105 K, suggesting strong interplay between structural distortion and spin correlations. In the critical regime between Ts and T_SDW, the dynamical structure factor of electron spins S(q,Wn) measured with the longitudinal NMR relaxation rate 1/T1 exhibits a divergent behavior obeying a power law, 1/T1~S(q, Wn)~(T/T_SDW-1)^a with the critical exponent a ~ 0.33.

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F. L. Ning, M. Fu, D. A. Torchetti, T. Imai, A. S. Sefat, P. Cheng, B. Shen, H. -H Wen. 2014-06-14. Critical Behavior of the SDW Transition in Underdoped Ba(Fe1-xCox)2As2 (x <=0.05): 75As NMR Investigation. https://doi.org/10.1103/physrevb.89.214511

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