Modulation of magnetic and dielectric properties by Al3+ substitution in Ca3CoMnO6 ceramics

Abstract

We report a detailed study of the influence of non-magnetic Al3+ doping on the microstructure, magnetic, and dielectric characteristics Ca3CoMnO6. The introduction of Al3+ leads to the suppression of competing short-range magnetic orders, a gradual disappearance of the spin freezing peak in Ca3CoMn1-xAlxO6 was observed, accompanied by the release of magnetic frustration. Moreover, a weakening of the antiferromagnetic order in Ca3CoMnO6 was attributed to the dilution effect induced by non-magnetic Al3+ within the Co-Mn-Co-Mn spin chains. The dielectric measurements exhibit excellent agreement with the magnetic measurements. The substitution of Mn4+ with Al3+ results in the attenuation of relaxor ferroelectric behavior, accompanied by a decrease in the static freezing temperature Tf and an increase in the activation energy Ea. It indicates that Al3+ substitution could well suppress the formation of polar nanoregions. With introducing Al3+ the magnetodielectric effect of Ca3CoMnO6 is also significantly enhanced. For the x = 0.15 sample, the magnetodielectric effect undergoes a notable variation of approximately 10 % under a magnetic field of H = 4 T.