Magnetic and magneotransport properties of Nd0.75Na0.25MnO3 manganite

We report the magnetic and magnetotransport properties of the polycrystalline manganite Nd0.75Na0.25MnO3. In zero field, the sample shows a ferromagnetic insulator behavior. Under applied fields higher than 30 kOe, a field-induced insulator-metal, followed by a metal-insulator transition at a lower temperature occur; at the same time the colossal magnetoresistance (CMR) effect is also observed. At the temperature of 5 K, the metamagnetic transition from charge ordering/antiferromagnetic (CO/AFM) to ferromagnetic (FM) state is observed. With increasing temperature, the metastable FM phase can transform back to the CO state, accompanied by a high field hysteresis. The CMR effect of the sample can be understood by a percolative regime and is related to the CO-FM transition under a large magnetic field.