Time effects in 57Fe NMR in YFeO3

The NMR of 57Fe has been studied in a thin single crystal plates of YFeO3 by spin echo and steady-state methods at the temperature range of 1.8-450K. The observed signals undergo a change after the application of a weak magnetic DC field. The new state is unstable. The recovery time at 77K is about 0.5h and decreases with increasing temperature. Below 77K these effects disappear. In the unstable state, enhancement factor eta is twice as large as before the field application. Spin echo signal does not increase but the amplitude of radiopulses required for the forming of spin echo signal decreases. This fact suggests that the volume of domain walls decreases. At 1.8K some features characteristic for the phase transition were noticed