Composition-, temperature-, and field- driven magnetic phase transitions in Bi0.9Ca0.1Fe1-xMnxO3 multiferroics

•Mn substitution induces polar-antipolar transition in Bi0.9Ca0.1Fe1-xMnxO3 at x = 0.45.•Cycloidal, collinear or canted AFM order can be stabilized depending on Mn content.•Magnetic structure changes depending on temperature and magnetic field. A magnetometric study of Bi0.9Ca0.1Fe1-xMnxO3 (0.3 ≤ x ≤ 0.5) compounds was conducted over broad temperature and field ranges to clarify the impact of Mn substitution on the magnetic properties of Ca2+-doped bismuth ferrite-based multiferroics near the polar-antipolar phase boundary. Room-temperature X-ray diffraction measurements confirm the stability of the polar rhombohedral R3c structure up to x = 0.4, with a transition to the antipolar orthorhombic Pnam phase occurring through a mixed structural state at x≈ 0.45. Magnetic measurements of rhombohedral-structure samples reveal an evolution in magnetization behavior, indicative of a transformation from the cycloidal spin order, characteristic of low-doped bismuth ferrites, to a collinear antiferromagnetic arrangement as Mn content increases. Magnetic field modifies the collinear antiferromagnetic structure towards a canted antiferromagnetic one. The threshold field for the metamagnetic transformation decreases with decreasing temperature and increasing Mn concentration.