Unusual metamagnetic transitions in Pr0.5 Ca0.5 Mn0.97 Ga0.03 O3 studied by pulsed magnetic fields

Several unusual and intriguing magnetic phenomena have been observed in the Ga-doped manganite Pr0.5 Ca0.5 Mn0.97 Ga0.03 O3. First, at 2.5 K, the magnetization steps and plateaus observed in the conventional M (H) measurements with a sweep rate of less than 1 T/s are readily suppressed under an ultrafast magnetic field with a sweep rate of ∼ 103 T/s. This feature is correlated with the collapse of the balance between the magnetic energy and the elastic energy within the martensiticlike scenario. Second, the zero-field cooled M (H) curve consists of two metamagnetic features, which were not observed in the conventional low-field magnetization measurements and might be associated with the coexistence of the pseudo-CE-type and the CE-type antiferromagnetic phases. Third, both the antiferromagnetic and ferromagnetic phases may coexist under certain combinations of the magnetic field and temperature. The temperature-field phase diagram exhibits a minimum critical field for the antiferromagnetic to ferromagnetic transition. Similarities with other magnetic phase-separated systems are pointed out.