Steplike magnetization and resistivity transition in the half-doped manganite compound Pr0.75Na0.25MnO3

We report on the magnetic and electrical transport properties of a half-doped manganite Pr0.75Na0.25MnO3. At low temperatures, a field-induced steplike magnetization and resistivity transition are observed. The step transitions of magnetization and resistivity are shifted to higher fields as a result of field cooling, and transformed to a smooth broad one when the cooling field is more than 20 kOe. Moreover, in a magnetic field slightly below the critical field, the magnetic and resistive relaxation exhibits a spontaneous step after a long incubation time when both the temperature and magnetic field are constant. Such steplike transitions are discussed in terms of a martensitic-like transformation associated with phase separation.