Hyperfine interactions and irreversible magnetic behavior in multiferroic Aurivillius compounds
Multiferroics in which ferroelectric and ferro(antiferro-) magnetic (and/or ferroelastic) properties are simultaneously combined in one material are a subject of intensive research due to prospective applications as, e.g. next-generation memory storage materials [11]. The Aurivillius phases of the Bi4Ti3O12-BiFeO3 system are described by the general formula Bim+1Ti3Fem–3O3m+3 where m denotes the number of perovskite-like layers per slab and 3 ≤ m ≤ 13 [5]. With increasing m significant changes occur in the physical properties of these materials, e.g. the lattice parameter c of the orthorhombic unit cell increases from 32.80 A for m = 3 up to 81.25 A for m = 9 [5]. The compounds are semiconductors with two phase transitions in the temperature ranges of 933–1033 K and 1073–1123 K confirmed by differential scanning calorimetry and temperature dependencies of dielectric constant [4]. It was found that the ferroelectric Curie temperature TC increases with m number, then decreases for m = 4–6 and for m > 6 a plateau in the dependence TC(m) can be observed [5]. While the structure, thermal stability and electric properties of the Aurivillius compounds are relatively well known, their magnetic properties are still not well recognized. At room temperature these compounds combine the ferroelectric and antiferromagnetic propHyperfine interactions and irreversible magnetic behavior in multiferroic Aurivillius compounds Elzbieta Jartych, Karolina Gąska, Janusz Przewoźnik, Czeslaw Kapusta, Agata Lisinska-Czekaj, Dionizy Czekaj, Zbigniew Surowiec