Metamagnetic phase transitions induced by static and pulsed fields in (Sm0.5Gd0.5)0.55Sr0.45MnO3 ceramics

Abstract

It has been found that the magnetic susceptibility of (Sm 0.5 Gd 0.5 ) 0.55 Sr 0.45 MnO 3 ceramic samples in zero external magnetic field exhibits a sharp peak near the temperature of 48.5 K with a small temperature hysteresis that does not depend on the frequency of measurements and is characteristic of the phase transition to an antiferromagnetic state with a long range charge orbital ordering, which is accompanied by an increase in the magnetic susceptibility with a decrease in the temperature. The magnetization isotherms in static and pulsed magnetic fields at temperatures below 60 K demonstrate the occurrence of an irreversible metamag netic transition to a homogeneous ferromagnetic state with a critical transition field independent of the mea surement temperature, which, apparently, is associated with the destruction of the insulating state with a long range charge ordering. In the temperature range 60 K ≤ T ≤ 150 K, the ceramic samples undergo a mag netic field induced reversible phase transition to the ferromagnetic state, which is similar to the metamag netic transition in the low temperature phase and is caused by the destruction of local charge/orbital corre lations. With an increase in the temperature, the critical transition fields increase almost linearly and the field hysteresis disappears. Near the critical fields of magnetic phase transitions, small ultra narrow magnetization steps have been revealed in pulsed fields with a high rate of change in the magnetic field of ~400 kOe/μs.