Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Collaborative Innovation Center of Quantum Matter, Beijing, China.
Phys Rev Lett. 2015 Apr 17;114(15):157002. doi: 10.1103/PhysRevLett.114.157002.
We use nuclear magnetic resonance (NMR), high-resolution x-ray, and neutron scattering studies to study structural and magnetic phase transitions in phosphorus-doped BaFe2(As(1-x)P(x)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 (T{s}) and paramagnetic to antiferromagnetic (AF, TN) transitions in BaFe2(As(1-x)Px)2 are always coupled and approach T{N}≈T{s}≥T{c} (≈29 K) for x=0.29 before vanishing abruptly for x≥0.3. These results suggest that AF order in BaFe_{2}(As(1-x)Px)2 disappears in a weakly first-order fashion near optimal superconductivity, much like the electron-doped iron pnictides with an avoided QCP.
我们使用核磁共振（NMR）、高分辨率 X 射线和中子散射研究来研究磷掺杂 BaFe2(As(1-x)P(x)2 中的结构和磁相变。以前的输运、NMR、比热和磁穿透深度测量为 x=0.3 附近的最佳超导性附近存在量子临界点 (QCP) 提供了令人信服的证据。然而，我们表明 BaFe2(As(1-x)Px)2 中的四方到正交结构 (T{s}) 和顺磁到反铁磁 (AF, TN) 转变总是耦合的，并且在 x≥0.3 之前，对于 x=0.29，T{N}≈T{s}≥T{c}（≈29 K）突然消失。这些结果表明，BaFe_{2}(As(1-x)Px)2 中的 AF 序在最佳超导性附近以弱一级方式消失，类似于具有规避 QCP 的电子掺杂铁磷化物。
