Evolution of spin-modulated magnetic structure in multiferroic compound Bi(1−x)SrxFeO3

BiFeO3 is a perovskite-like compound with magnetic and electrical long-range order with antiferromagnetic transition temperature about 670 K. It has space modulated magnetic structure of cycloidal type with the period λ = 620 ± 20 Å incommensurate with the lattice parameter leading to specific NMR line shape. Substitution of strontium for bismuth atoms destroys the space modulated structure. Several samples with substitution of strontium for bismuth Bi1−xSrxFeO3 were studied by means of zero field NMR and Mössbauer spectroscopy. A significant broadening of 57Fe NMR spectrum was observed at x = 0.10 while Mössbauer spectroscopy demonstrates this effect at x = 0.07 . This phenomena evidence for the destruction of the spatial modulated magnetic structure at x ∼ 0.07 –0.10 by the heterovalent substitution of strontium for bismuth without the destruction of crystal rhombohedral structure.