Spin magnetic susceptibility of Cu-O chains in Sr2CuO3 and SrCuO2

We show that the spin magnetic susceptibility of Sr2CuO3 and SrCuO2 with Cu-O chains is in excellent agreement with the theoretical calculation by Eggert, Affleck, and Takahashi on the S=1/2 antiferromagnetic Heisenberg chain. Both compounds have extraordinarily large exchange interaction energy J similar to 2200 K and reduced Neel temperature T-N < 5 K. In Sr2CuO3, a logarithmic correction, predicted by the theory, is clearly identified at low temperatures below 0.01 J similar to 20 K.