Magnetic short and long range order in a disordered perovskite

PbFe$_{1/2}$Ta$_{1/2}$O$_{3}$ (PFT) belongs to the family of PbB$'_{x}$B$''_{1-x}$O$_{3}$ perovskites with inherent chemical disorder at the B-site. We have studied the magnetic phase diagram of PFT through macroscopic techniques, neutron scattering and M\"ossbauer spectroscopy. We show that PFT undergoes two phase transitions: paramagnetic to antiferromagnetic transition at T$_{N}\sim$153K and a spinglass transition at T$_{SG}\sim$10K. Below T$_{SG}$, antiferromagnetism coexists with spinglass on microscopic scale. We suggest that the arrangement of magnetic moments in this unusual ground state of PFT is a speromagnet-like, similar to the one proposed for PbFe$_{1/2}$Nb$_{1/2}$O$_{3}$.\footnote{S. Chillal, M. Thede, F. J. Litterst, S. N. Gvasaliya, T. A. Shaplygina, S. G. Lushnikov, and A. Zheludev, Phys. Rev. B 87, 220403 (2013).}