paper

Structural and magnetic phase transitions near optimal superconductivity in BaFe $_{2}$ (As $_{1 - x}$ P $_{x}$ ) $_{2}$

arXiv:1503.08947 · doi:10.1103/PhysRevLett.114.157002

Abstract

We use nuclear magnetic resonance (NMR), high-resolution x-ray and neutron scattering to study structural and magnetic phase transitions in phosphorus-doped BaFe $_{2}$ (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, $T_{N}$ ) transitions in BaFe $_{2}$ (As $_{1 - x}$ P $_{x}$ ) $_{2}$ are always coupled and approach to $T_{N} \approx T_{s} \geq T_{c}$ ( $\approx 29$ K) for $x = 0.29$ before vanishing abruptly for $x \geq 0.3$ . These results suggest that AF order in BaFe $_{2}$ (As $_{1 - x}$ P $_{x}$ ) $_{2}$ disappears in a weakly first order fashion near optimal superconductivity, much like the electron-doped iron pnictides with an avoided QCP.

8 pages, 8 figures. including supplementary, Accepted by Physical Review Letters

Structural and magnetic phase transitions near optimal superconductivity in BaFe2​(As1−x​Px​)2​

Abstract

Structural and magnetic phase transitions near optimal superconductivity in BaFe $_{2}$ (As $_{1 - x}$ P $_{x}$ ) $_{2}$