Aliovalent Calcium Substitution: An Effective Way to Enhance the Magnetoelectric Coupling Properties of Multiferroic BiFeO3

Kinetics of magnetoelectric coupling in bismuth ferrite (BiFeO3) with the substitution of aliovalent calcium ion is investigated. The resulting structural, dielectric, magnetic, and magnetoelectric (ME) coupling properties are explained in terms of chemical pressure originating from the substituent ion. Substitution of calcium finds to reduce the oxygen vacancies. Two important substitution concentrations find to be critical in ferroelectric (FE) and ME coupling properties. At 10 at% calcium, highest remanent polarization is obtained and maximum ME coupling coefficient is observed at 20 at%, which suggests calcium concentration between 10% and 20% can be optimized to obtain good electrical and ME coupling properties of BiFeO3. Maximum ME coupling coefficient at calcium concentration 20 at% is close to numerical calculations reported in the literature. Magnetic properties are also favorably modified by the substitution; a coupled antiferromagnetic and weak ferromagnetic ordering is obtained. Also, a variation in blocking temperature and spin relaxation is observed with respect to the substituent ion concentration.

Automated summary

The kinetics of magnetoelectric coupling in bismuth ferrite with the substitution of calcium ions was investigated. The study explained the resulting properties in terms of chemical pressure caused by the substituent ion and found that calcium substitution reduced the oxygen vacancies. Two critical substitution concentrations were identified for the ferroelectric and magnetoelectric properties. The study suggests that a calcium concentration between 10% and 20% can be optimized to obtain good electrical and magnetoelectric coupling properties. The magnetic properties were also modified favorably, and a coupled antiferromagnetic and weak ferromagnetic ordering was observed.