Phosphor induced significant hole-doping in ferropnictide superconductor BaFe2(As(1-x)Px)2

TL;DR

This study reveals that phosphor doping in BaFe2(As1-xPx)2 introduces significant hole carriers, challenging the notion of iso-valent doping and providing insights into the nodal superconducting gap in this high-temperature superconductor.

Contribution

It demonstrates that phosphor substitution induces hole doping in BaFe2(As1-xPx)2, overturning the belief that iso-valent doping does not alter charge carrier concentration.

Findings

Phosphor doping introduces sizable holes into the Fermi surfaces.

The dxy-originated band remains relatively intact after doping.

The phase diagram resembles hole-doped compounds, contradicting previous assumptions.

Abstract

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.