The Effect of Magnetic Anisotropy on Colossal Electroresistance in Manganites

The combined effect of long range strain interactions and disorder on a first order transition leads to micrometer scale phase separation in hole-doped manganese oxides (manganites). The coexisting phases are ferromagnetic metallic (FMM), charge ordered insulating (COI), and paramagnetic insulating (PMI) and at certain temperatures these phases behave like a fluid under the influence of magnetic and electric fields. We will present magnetotransport data on nano/micro-structures of the manganite (La$_{1-y}$Pr$_{y})_{0.67}$Ca$_{0.33}$MnO$_{3}$ (LPCMO) which show that the FMM phase behaves like a fluid in an electric field. In fact, due to the magnetic anisotropy of our materials, the behavior of the coexisting phases is reminiscent of a ferrofluid.