Impurity Substitution Effect on Magnetoelectric Properties of CaBaCo4O7 Crystals

Abstract We have investigated effects of impurity substitution of Fe for Co sites on magnetic and dielectric properties in CaBa(Co 1- x Fe x ) 4 O 7 crystals in magnetic fields. The non-doped compound, CaBaCo 4 O 7 with the polar space group Pbn 2 1 , shows a large change of electric polarization ΔP along the c axis below a ferrimagnetic transition temperature. With increasing x , the transition temperatures for the ferrimagnetic and ferroelectric-like phases are shifted towards lower and these phases are completely collapsed above x =1.56%. We have also investigated the magnetic field effects for CaBa(Co 1- x Fe x ) 4 O 7 crystal with a doping level x =0.5% where the ferrimagnetic and ferroelectric-like phases sustain. Then a relatively large magnetocapacitance, Δɛ ( H )/ ɛ (0) [ ɛ ( H ) – ɛ (0)]/ ɛ (0), of 45% at 58 K was observed, which is not significantly reduced from the parent compound.