Suppression of long range magnetic order accompanying structural transition in TbFeAs1-xPxO*

We report the results of neutron scattering on powder samples of TbFeAs1-xPxO. Many pnictide superconductors share a ubiquitous set of traits in their parent compounds. The un-doped parent compounds exhibit a structural transition from tetragonal to orthohombic between ~100-200K related to an antiferromagnetic spin density wave ordering that is either concurrent with the structural transition or at a slightly lower temperature. We find no evidence through neutron diffraction of this magnetic order at typical length scales in the Tb-1111 system. The sensitivity of our measurements allows us to rule out ordered magnetic moments above 0.08 µB. Furthermore, suppression of the structural transition by isovalent doping of phosphorous onto the arsenic site has shown no evidence of inducing the common superconductivity seen with similar doping in related materials down to 1.8K.