Magnetization reversal, giant exchange bias effect and magnetoresistance in oxygen vacancy ordered Sr${}_4$Fe${}_3$CoO${}_{11}$

Abstract

We report the structural, magnetic, exchange bias and magnetotransport effect in Sr${}_4$Fe${}_3$CoO${}_{11}$. The material crystallizes in the orthorhombic $\text{Cmmm}$ space group. It shows antiferromagnetic (G-type) transition (T${}_N$ = 255 K) along with interesting temperature induced magnetization reversal (T${}_{Comp.}$= 47 K measured at 100 Oe). The magnetic reversal can be elucidated considering the increased magnetocrystalline anisotropy with Co substitution. Magnetoresistance measurements shows an interesting crossover from negative to positive side at $\sim$ 100 K. The negative magnetoresistance reaches 80 $\%$ at 25 K in 7 T magnetic field. Giant exchange bias effect is observed below T${}_N$ under field cooling condition. The origin of the negative magnetoresistance and giant exchange bias in this sample can be attributed to the magnetic frustration.

6 Pages, 7 figures