Mössbauer studies of multiferroics BiFe1 – xCrxO3 (x = 0–0.20)

Resumo

The Mössbauer studies on ⁵⁷Fe nuclei in multiferroics BiFe_{1 – x}Cr_xO₃ (x = 0.05, 0.10, and 0.20) have been performed at room temperature. The multiferroics BiFe_{1 – x}Cr_xO₃ (x = 0.05, 0.10, and 0.20) with the rhombohedral R3c structure have been prepared by solid-state synthesis under high pressures. The effect of substitution of Cr cations for Fe cations on the spatial spin-modulated structure, and also hyperfine electrical and magnetic interactions of ⁵⁷Fe nuclei has been studied. The substituted ferrites demonstrate an anharmonic modulated spin structure of cycloid type, in which iron atoms with different cation environments take part. The anharmonism parameter of the cycloid linearly increases from m = 0.10 at x = 0 to m = 0.78 ± 0.02 at x = 0.20. The constants of magnetic uniaxial anisotropy K_u are estimated at room temperature: K_u ≈ 0.36 × 10⁶ erg/cm³ at x = 0 and K_u ≈ 4.22 × 10⁶ erg/cm³ at x = 0.20.