Abstract:
Multiferroics are systems in which more than one ferroic order simultaneously coexists. In this
project, we investigated some potentially multiferroic Swedenborgite systems with general
formulae ABM4O7.For this purpose we synthesized a series of polycrystalline sample of
swedenborgites DyxCa(1-x)BaCo4O7 (x = 0 to 1) using solid state ceramic synthesis. Structural
investigations of this series reveal that the as x changes from 0 to 1, the structure of the series
changes from a less symmetric orthorhombic Pbn21 to a more symmetric hexagonal P63mc.
Magnetisation measurements (ZFC-FC and MH) shows that the two end members of the series
CaBaCo4O7 and DyBaCo4O7 have a ferrimagnetic and a spin-glass ground states respectively. For
the compounds with (0.1 < x < 9) the MH curves at 2K shows a non-saturating spin glass like
behaviour. The high paramagnetic contribution of Dy3+ species mask transitions in the Co
sublattice, but an attempt have been made to understand the magnetic properties of some
systems by subtracting its paramagnetic contribution. Careful ac-susceptibility measurements
would be required to clearly establish the magnetic phase diagram in this series of compounds.
