Arsenic nuclear magnetic resonance in CaFe2As2

We present 75As nuclear magnetic resonance measurements in the paramagnetic and commensurate antiferromagnetic states of CaFe2As2. Single crystals were produced using a Sn flux method and characterized via powder X-Ray diffraction, susceptibility, and specific heat measurements. The NMR data show that the internal hyperfine field and electric field gradient change discontinuously at T0 = 169K. The observed hyperfine field is consistent with stripelike antiferromagnetic ordering of the Fe spins in the ab plane. Spin lattice relaxation data show metallic T1-1 $\sim $ T for T($<\sim )$ T0/3. However, T1-1 shows a small peak at 10K attributed to slow spin fluctuations that could indicate the emergence of antiferromagnetic domain wall motion.