Neutron scattering evidence for magnetic-field-driven abrupt magnetic and structural transitions in a phase-separated manganite

Substitutions at the Mn site of the charge-ordered Pr_0.5Ca_0.5MnO₃ manganite is an effective way to induce abrupt jumps on the magnetic-field-driven magnetization curve. In order to get new insights into the origin of this remarkable feature, the Pr_0.5Ca_0.5Mn_0.97Ga_0.03O₃ perovskite manganite has been studied by neutron diffraction versus temperature and at 2.5 K in an applied magnetic field up to 6 T. A weak and complex antiferromagnetic order is found for the low-temperature ground state. Magnetic transitions, associated with structural ones, are evidenced for certain strengths of magnetic field, which gives rise to the steplike behavior corresponding to the magnetization curve. Small-angle neutron scattering provides evidence for a nucleation process of micron-size ferromagnetic domains which follows the magnetization behavior.