We use nuclear magnetic resonance (NMR), high-resolution x-ray and neutron scattering to study structural and magnetic phase transitions in phosphorus-doped BaFe2(As1−xPx)2. Previous transport, NMR, specific heat, and magnetic penetration depth measurements have provided compelling evidence for the presence of a quantum critical point (QCP) near optimal superconductivity at x=0.3. However, we show that the tetragonal-to-orthorhombic structural (Ts) and paramagnetic to antiferromagnetic (AF, TN) transitions in BaFe2(As1−xPx)2 are always coupled and approach to TN≈Ts≥Tc (≈29 K) for x=0.29 before vanishing abruptly for x≥0.3. These results suggest that AF order in BaFe2(As1−xPx)2 disappears in a weakly first order fashion near optimal superconductivity, much like the electron-doped iron pnictides with an avoided QCP.
@article{arxiv.1503.08947,
title = {Structural and magnetic phase transitions near optimal superconductivity in BaFe$_2$(As$_{1-x}$P$_x$)$_2$},
author = {Ding Hu and Xingye Lu and Wenliang Zhang and Huiqian Luo and Shiliang Li and Peipei Wang and Genfu Chen and Fei Han and Shree R. Banjara and A. Sapkota and A. Kreyssig and A. I. Goldman and Z. Yamani and Christof Niedermayer and Markos Skoulatos and Robert Georgii and T. Keller and Pengshuai Wang and Weiqiang Yu and Pengcheng Dai},
journal= {arXiv preprint arXiv:1503.08947},
year = {2015}
}
Comments
8 pages, 8 figures. including supplementary, Accepted by Physical Review Letters