Zero-field La-139 nuclear magnetic resonance in La1-xCaxMnO3 for 0.125 <= x <= 0.5

The zero-field La-139 nuclear magnetic resonance (NMR) was studied in polyc rystalline La1-xCaxMnO3 for 0.125 less than or equal to x less than or equa l to 0.5 to investigate magnetic phases in ordered states. The main result of this work is that mixed states are found near any phase transition bound ary induced by either temperature or hole doping. The analysis of the NMR s ignal intensity and resonance frequency provides the evidence for ferromage ntic clusters or magnetic polarons near the ferromagnetic transition temper ature (T-C) The drastic change of the enhancement factor crossing the phase boundary at x = 0.2 implies the existence of single domain ferromagnetic m icroregions imbedded in an antiferromagnetic host for x<0.2. The comparison of NMR signal intensity with bulk magnetization shows that the macroscopic antiferromagnetic phase at x= 0.5 is a mixed state of microscopic ferromag netic and antiferromagnetic phases. [S0163-1829(99)01801-9].