Magnetic properties and dopant-dependent exchange bias in Ti-doped charge ordered Bi0.4Ca0.6MnO3

Magnetic properties of charge ordered (CO) Bi0.4Ca00.6Mn1-xTixO3 (0 ≤ x ≤ 0.2) are investigated. It is observed that the charge order temperature Tco is depressed gradually with Ti content increasing, and then disappears completely when x is 0.16. The high temperature magnetization and Curie temperature decrease with Ti content, whereas the low temperature magnetization and Curie temperature are increased. Moreover, exchange bias (EB) is observed in the field cooling mode for all samples. The relative EB parameters depend strongly on the Ti doping content. In particular, the exchange field shows a nonmonotonic variation with a maximum at Bi0.4Ca0.6Mn0.92Ti0.08O3. The EB has been explained in terms of the density of ferromagnetic nanodomains superposed on the antiferromagnetic matrix. The results suggest that it is possible to tune the EB through the Mn-site doping in CO manganites by controlling the density of ferromagnetic nanodomains.