Table 2: Iron isotope effect on TSDW and TC

From: A large iron isotope effect in SmFeAsO1 - xFx and Ba1 - xKxFe2As2

Table 2
  1. Shown are TSDW and TC, and their shifts (TSDW and TC) and αSDW and αC for the SmFeAsO1 - xFx samples with natural abundance oxygen nO and 18O, and 56Fe and 54Fe, and for the Ba1 - xKxFe2As2 samples with 54Fe and 56Fe, respectively. We calculated isotope exponents using α = -dlnT/dlnM, where M is the atomic mass. To guarantee that the intrinsic isotope effect is what is being measured, isotope back-exchange is usually used: the transition should return to that before isotope exchange. In our case, there is no way of carrying out the isotope back-exchange experiment. To obtain the intrinsic isotope effect, we prepared several batches of samples to check that the results are reproducible from sample to sample. Although TC varies slightly from batch to batch for SmFeAsO0.85F0.15, the TC shift caused by isotope exchange is nearly the same for all batches. TC for the sample Ba0.6K0.4Fe2As2 is very stable and nearly independent of batches. In the calculation the molar masses used are the same as used in Table 1 except for 18O, reduced to 17.42 g and 17.54 g because the isotope replacement was only 71% and 77%. The error bar for the temperature determination is equal to the step temperature in the temperature sweep: 0.02 K for TC and 0.05 K for TSDW in the resistivity measurements, respectively.