Cryogenic temperature relaxor-like dielectric responses and magnetodielectric coupling in Aurivillius Bi₅Ti₃FeO ₁₅ multiferroic thin films

Dielectric responses and magnetodielectric (MD) behavior of Aurivillius Bi₅Ti₃FeO₁₅ multiferroics were systemically studied at cryogenic temperatures. Dielectric anomaly at ∼145K was found by the temperature dependent dielectric spectroscopy, and relaxor-like relaxation dynamics was further confirmed unambiguously. Besides the two abnormal MD transitions at about 98K and 220K, remarkable MD couplings were observed near relaxation peak over the whole frequency range of 10²-10⁶ Hz. Finally, the possible mechanisms of the relaxation and MD properties were discussed in association with the occurrence of local Fe-O nano-clusters because of the antisite disorder defects in Aurivillius multiferroic phases.