Investigation of the potentially multiferroic Swedenborgite SysteMS

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.