Magnetization reversal, giant exchange bias effect and magnetoresistance in oxygen vacancy ordered Sr4Fe3CoO11

6 Pages, 7 figuresInternational audienceWe report the structural, magnetic, exchange bias and magnetotransport effect in Sr4Fe3CoO11.
 The material crystallizes in the orthorhombic Cmmm space group. It shows antiferromagnetic (G-type)
 transition (TN = 255 K) along with interesting temperature induced magnetization reversal
 (TComp:= 47 K measured at 100 Oe). The magnetic reversal can be elucidated considering the increased
 magnetocrystalline anisotropy with Co substitution. Magnetoresistance measurements show
 an interesting crossover from negative to positive side at ~100 K. The negative magnetoresistance
 reaches 80 % at 25 K in 7 T magnetic field. Giant exchange bias effect is observed below TN under
 field cooling condition. The origin of the negative magnetoresistance and giant exchange bias in this
 sample can be attributed to the magnetic frustration