Giant exchange bias effect with low-coercivity in YbBaCo4O7

We observe significant exchange-bias effect below ∼ 76 K in antiferromagnetic YbBaCo4O7. Exchange-bias field (HE) is ∼ 10 kOe for 50 kOe cooling-field (Hcool) at 4 K. The HE increases considerably with Hcool associated with the nominal increase of coercivity (HC). Low HC provides high value of HE/HC (∼ 15) at 4 K. High HE/HC ratio and nominal increase of HC are appealing. The results suggest robust EB effect associated with the minimal occurrence of inhomogeneous micro-domains, which is potential for the applications. Magnetic phase separation between antiferromagnetic components with k1 = (0, 0, 0) and k2 = (1/2, 0, 0) propagation vectors of the Pbn21 space group is correlated with the exchange-bias effect.