Exchange bias training effect in phase separated polycrystalline Sm_0.1Ca_0.7Sr_0.2MnO₃

Magnetic properties of antiferromagnetic (AFM) electron doped manganite Sm_0.1Ca_0.7Sr_0.2MnO₃ have been investigated, focusing mainly on the exchange bias (EB) effect and associated training effect. The studied compound exhibits the ground state with heterogeneous spin configuration, consisting of the C-type antiferromagnetic phase with the Néel temperature T_N-C ≈ 120 K, the G-AFM phase with the Néel temperature T_N-G ≈ 60 K, and ferromagnetic-like phase with a very weak spontaneous magnetic moment. Measurements of hysteresis loops have shown that the exchange bias field monotonously decreases with increasing temperature and vanishes above 40 K, while the coercivity disappears only above 70 K. The temperature variation of the exchange bias field has been successfully described by an exponential decay form. The stability of EB has been evaluated in the studies of the training effect, which has been discussed in the frame of the spin relaxation model, elucidating the important role of the AFM domain rearrangement at the interface. The complex phase separation and possible contributions from different interfaces between coexisting magnetic phases to the EB effect have also been discussed.