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(1-x)(0.94Bi0.5Na0.5TiO3-0.06BaTiO3)-xBiFeO3 (0 ≤ x ≤0.9) ternary ceramics were prepared by the modified Pechini method. X ray diffraction patterns manifest that the samples undergo a gradual structural transformation from the rhombohedral-tetragonal morphotropic phase boundary to the rhombohedral phase with the increasing content of BiFeO3. Room temperature ferromagnetism was observed in BiFeO3-rich samples with x ≥ 0.6, and this ferromagnetism can be ascribed to the suppression of the spiral spin structure with the canting of antiferromagnetically ordered spins. The BiFeO3-rich samples (x=0.6-0.8) exhibit superior ferroelectric properties with the maximum remanent polarization of 44.7 lC/cm², as confirmed by the positive-up negative-down measurement to exclude the contribution of leakage current. The coexistence of room-temperature ferromagnetism and ferroelectricity manifests that the lead-free BiFeO3-based solid solutions are quite promising multiferroic materials and may be important for potential applications in BFO-based magnetoelectric devices. [ABSTRACT FROM AUTHOR]

We report the detailed investigations of the magnetic properties, electronic transport, and specific heat in Zn-doped antiperovskite compounds Ga1-xZnxCMn3. Magnetic measurements indicate the metastability of the antiferromagnetic (AFM)-ferromagnetic intermediate (FI) phase transition and the coexistence of different magnetic phases at lower temperature. The enhanced giant magnetoresistance (GMR) is observed with a maximum value of 70% spanning a temperature range of 100 K at 50 kOe. The analysis of heat capacity reveals that the metastability of the AFM-FI transition and the enhanced GMR observed in Ga1-xZnxCMn3 may originate from the reconstruction of Fermi surface accompanying AFM-FI transition. [ABSTRACT FROM AUTHOR]

We report an enhanced negative giant magnetoresistance (GMR) with larger temperature span in Ni-doped antipervoskite compounds GaCMn3-xNix. The observed GMR can peak at ∼75% (at 85 kOe) and exceed 60% (at 50 kOe) over a temperature span of approximate 110 and 50K for x=0.05 and 0.10, respectively. Compared with the parent GaCMn3, the well-enhanced GMR in Ni-doped samples is suggested to be associated with the partially suppressed antiferromagnetic (AFM) ground state, which favors the transition from the high-resistivity AFM state to the low-resistivity canted ferromagnetic state under an external magnetic field. [ABSTRACT FROM AUTHOR]

The magnetic and dielectric properties of Bi6Fe2Ti3O18, Bi6FeCoTi3O18, and Bi5LaFeCoTi3O18 are investigated. The room-temperature ferromagnetism is observed in the samples Bi6FeCoTi3O18 and Bi5LaFeCoTi3O18 compared with the paramagnetic behavior in Bi6Fe2Ti3O18 at room temperature. The ferromagnetism in Bi6FeCoTi3O18 and Bi5LaFeCoTi3O18 can be ascribed to spin canting of the Fe-based and Co-based sublattices via the antisymmetric Dzyaloshinskii-Moriya interaction. The frequency-dependent behavior of the dielectric loss peak in Bi6FeCoTi3O18 and Bi5LaFeCoTi3O18 manifests itself a thermally activated relaxation process. The rather large activation energy (2.62 ± 0.11 eV for Bi6FeCoTi3O18 and 1.97 ± 0.07 eV for Bi5LaFeCoTi3O18) implies that the relaxation process is not due to the thermal motion of oxygen vacancies inside ceramics. [ABSTRACT FROM AUTHOR]