PHYSICAL REVIEW B, cilt.90, 2014 (SCI İndekslerine Giren Dergi)
We present neutron diffraction analysis of BaFe2(As1-xPx)(2) over a wide temperature (10 to 300 K) and compositional (0.11 <= x <= 0.79) range, including the normal state, the magnetically ordered state, and the superconducting state. The paramagnetic to spin-density wave and orthorhombic to tetragonal transitions are first order and coincident within the sensitivity of our measurements (similar to 0.5 K). Extrapolation of the orthorhombic order parameter down to zero suggests that structural quantum criticality cannot exist at compositions higher than x = 0.28, which is much lower than values determined using other methods, but in good agreement with our observations of the actual phase stability range. The onset of spin-density wave order shows a stronger structural anomaly than the charge-doped system in the form of an enhancement of the c/a ratio below the transition.