Critical behavior of the spin density wave transition in underdopedBa(Fe1−xCox)2As2(x≤0.05):As75NMR investigation Academic Article uri icon

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  • 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.


  • Ning, FL
  • Fu, M
  • Torchetti, DA
  • Imai, Takashi
  • Sefat, AS
  • Cheng, P
  • Shen, B
  • Wen, H-H

publication date

  • June 25, 2014