Antisite disorder driven magnetodielectric and magnetocaloric effect in double perovskite La2−xSrxCoMnO6 (x = 0.0, 0.5, 1.0)

Abstract

We report magnetic, dielectric, magnetodielectric, and magnetocaloric responses of La2CoMnO6 (LCMO) and Sr doped La2−xSrxCoMnO6 (x = 0.5 and 1.0) induced by antisite disorder. The antisite disorder is enhanced with Sr-doping at La-sites. Co ions have mixed valence states on Sr-doping, with Co3+ and Co2+. Mn is present in mixed valence of Mn4+ and Mn3+ states with Sr doping. The dielectric constant of Sr doped LCMO was found to increase, whereas the magnetodielectric coupling was found suppressed due to the increase of antisite disorder. The magnetic field-dependent magnetodielectric effect clearly shows M2 behavior for all the samples in the field range of 0 to ±6 T in their respective ferroic phases. All the samples show spin glass like ordering in the ground state. We also report the magnetic entropy change in magnetoelectric material La2−xSrxCoMnO6 (x = 0, 1.0) samples. The change in magnetic entropy ΔSm originates mainly from the combined effect of the ferromagnetic/antiferromagnetic interaction and the magnetodielectric effect in La2−xSrxCoMnO6 (x = 0, 1.0). The observed value of the magnetocaloric effect (1.2 J/kg K) for x = 1.0 is likely to originate from the antisite disordered phases near Curie temperature.