Origin of enhanced magnetization in (La,Co) codoped BiFeO3 at the morphotropic phase boundary

Structural transition and magnetic properties of Mn doped Bi0.88Sm0.12FeO3 ceramics

“…38 Two phonon modes at around 122 and 251 cm À1 should be related to the phonon vibration of the Pnam orthorhombic symmetry, because no impurity phase was detected in the BSFMO compounds. 19,39 Our observations are consistent with previous reports. 19,40 Therefore, these active modes of R3c symmetry can be assigned to the E-2(TO), E-2(LO), A 1 -2(TO), E-3(TO), E-4(TO), E-5(TO), E-7(TO), E-8(LO), E-9(TO), and E-9(LO), as denoted in Fig.…”

“…7 Therefore, an increase in the VHS at the MPB possibly occurs from magnetic coupling at the boundary or from the inhomogeneous magnetic anisotropy of the coexisting phase. 6,7,19 The self-change of magnetization with time has been previously observed in (La, Co), 19 (La, Ti), 9 and (La, Zn) codoped BFO at the MPB. 17 This effect is attributed to the isothermal structural transition along with spin frustration at the PB, which is an implication for the appearance of a PB ferromagnetic order embedded in the antiferromagnetic matrix.…”

“…31 No impurity phase was observed in the compounds within the detection limit of our XRD equipment. This suggests that the co-substitution of Sm and Mn at Bi and Fe sites can suppress the formation of the sillenite-type impurity phase such as Bi 25 FeO 4 and Bi 2 Fe 4 O 9 , which is contrary to (La, Co), 19 (Sm, Sc), 32 and (Ce, Cr) codoped BFO. 33 The inset of Fig.…”

“…17 This effect is attributed to the isothermal structural transition along with spin frustration at the PB, which is an implication for the appearance of a PB ferromagnetic order embedded in the antiferromagnetic matrix. 9,19 Magnetic coupling between two structural phases and the PB is similar to the interaction of the antiferromagnetic-ferromagnetic multilayer. 20 PB ferromagnetism and magnetic exchange anisotropy were used to explain the VHS, classical exchange bias effect, and eld step-dependent hysteresis loop.…”

“…20 PB ferromagnetism and magnetic exchange anisotropy were used to explain the VHS, classical exchange bias effect, and eld step-dependent hysteresis loop. 6,7,9,19 Moreover, the enhancement of magnetization at the MPB of BFO-based compounds can also be fullled by considering the contribution of PB ferromagnetism. 13,[21][22][23] To date, numerous attempts have been made to study the effects of Sm and Mn substitution on the crystal structure and on the ferroelectric and magnetic properties of BFO multiferroic.…”