Microscopic study of the effect of impurities on the first order spin density wave transition in BaFe2As2
Abstract
We report an 75As NMR study of BaFe2As2 in both single crystals and polycrystal forms. We find that Sn impurities in the single crystal dramatically alter the low energy spin fluctuations and suppress the ordering temperature from 138 K to 85 K. In contrast to Sn-free samples, we find that the temperature dependence of the 75As NMR spectra and spin lattice relaxation rates reveal a second order phase transition to a state of incommensurate magnetic order.
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