Observation of high coercivity in multiferroic lanthanum doped BiFeO3

• Published in: Journal of alloys and compounds 2013-03, Vol.554, p.271-276
• Main Authors: Suresh, Pittala, Srinath, S.
• Format: Article
• Language: English
• Subjects: Ceramics; Coercive force; Coercivity; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cusps; Dielectric properties; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Domain effects, magnetization curves, and hysteresis; Doping; Exact sciences and technology; Ferroelectrics; Ferromagnetism; Magnetic properties; Magnetic properties and materials; Magnetization; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Permittivity (dielectric function); Phase transition; Physics; Spin glass
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2012.11.129

► Two phase model is used to refine the structure. ► The quantitative estimates of phases as a function of doping are presented. ► Effect of La doping on the dielectric, magnetic properties is reported. ► High coercivity ∼1.5 Tesla is observed for La doped BiFeO3 samples. ► TN increases with increase in La doping. LaxBi1−xFeO3 (x=0.0–0.4) ceramics are synthesized by solid state reaction method. An increase in La results systematic decrease in rhombohedral (∼92.4% to ∼ 58.39%) and increase in orthorhombic phase (∼7.59% to ∼41.60%). The structural transition is further confirmed by the changes observed in Raman vibrational modes. A significant enhancement in the dielectric constant by two to three times is observed with La doping. Upon the La doping, the canted anti-ferromagnetic behavior of BiFeO3 turns to weak ferromagnetic. A huge enhancement in remanent magnetization (Mr) and coercivity (HC) of the order of 1.21T is observed even for a small doping of x=0.05. The improvement in the magnetic properties of La doped ceramics over BiFeO3 is due to the destruction of spin cycloid with the substitution of La. A cusp at 50K in the M–T curve reveals a spin glass nature of these samples. Anti-ferromagnetic Néel temperature (TN) increases with x. From the high temperature M–T curve, it is revealed that these ceramics exhibit a large magnetic irreversibility confirming the spin glass state.