Hu, DingLu, XingyeZhang, WenliangLuo, HuiqianLi, ShiliangWang, PeipeiChen, GenfuHan, FeiBanjara, Shree R.Sapkota, A.Kreyssig, A.Goldman, A.I.Yamani, Z.Niedermayer, ChristofSkoulatos, MarkosGeorgii, RobertKeller, T.Wang, PengshuaiYu, WeiqiangDai, Pengcheng2016-06-102016-06-102015Hu, Ding, Lu, Xingye, Zhang, Wenliang, et al.. "Structural and Magnetic Phase Transitions near Optimal Superconductivity in BaFe2(As1−xPx)2." <i>Physical Review Letters,</i> 114, no. 15 (2015) American Physical Society: 157002. http://dx.doi.org/10.1103/PhysRevLett.114.157002.https://hdl.handle.net/1911/90490We use nuclear magnetic resonance (NMR), high-resolution x-ray, and neutron scattering studies 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 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.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttp://dx.doi.org/10.1103/PhysRevLett.114.157002