The superconductivity in high temperature superconductors ordinarily arises when doped with hetero-valent ions that introduce charge carriers. However, in ferropnictides, "iso-valent" doping, which is generally believed not to introduce charge carriers, can induce superconductivity as well. Moreover, unlike other ferropnictides, the superconducting gap in BaFe2(As1-xPx)2 has been found to contain nodal lines. The exact nature of the "iso-valent" doping and nodal gap here are key open issues in building a comprehensive picture of the iron-based high temperature superconductors. With angle-resolved photoemission spectroscopy (ARPES), we found that the phosphor substitution in BaFe2(As1-xPx)2 induces sizable amount of holes into the hole Fermi surfaces, while the dxy-originated band is relatively intact. This overturns the previous common belief of "iso-valent" doping, explains why the phase diagram of BaFe2(As1-xPx)2 is similar to those of the holedoped compounds, and rules out theories that explain the nodal gap based on vanishing dxy hole pocket.
@article{arxiv.1105.5242,
title = {Phosphor induced significant hole-doping in ferropnictide superconductor BaFe2(As(1-x)Px)2},
author = {Z. R. Ye and Y. Zhang and M. Xu and Q. Q. Ge and F. Chen and Juan Jiang and B. P. Xie and J. P. Hu and D. L. Feng},
journal= {arXiv preprint arXiv:1105.5242},
year = {2015}
}