Exchange bias effect in CaMn 1-x Re_xO₃

Exchange bias effect in CaMn_1-xRe_xO₃ (x ≤ 0.1) has been investigated. The effect is very small in the samples doped at x = 0.02 and 0.04, but increases monotonously with further increase in Re doping. For x = 0.1, both vertical and horizontal shifts in hysteresis loop of field cooled sample decrease monotonously with increasing temperature and vanish above 70 K, while coercivity disappears only above 90 K upon approaching the Néel temperature. Exchange bias field, coercivity, and remanence asymmetry depend sensitively on temperature and maximal measuring field. Magnetic training effect has been studied for x = 0.06, 0.08, 0.1 samples and analyzed using a spin relaxation model. The observed exchange bias is attributed to the low-temperature phase separation into ferromagnetic clusters and the G-type and/or C-type antiferromagnetic matrix.