FIRST-ORDER NUCLEATION OF CHARGE-ORDERED DOMAINS IN LA0.5CA0.5MNO3 DETECTED BY LA-139 AND MN-55 NMR

The local magnetism and charge ordering of La0.5Ca0.5MnO3, was investi gated between room temperature and 1.3 K by means of La-139 and Mn-55 NMR. Antiferromagnetic and ferromagnetic domains are assigned unambigu ously to the insulating charge ordered and the metallic state respecti vely. The phases are found to coexist at all temperatures below the fi rst formation of a charge-ordered state. The two signal fractions disp lay thermal and magnetic hysteresis, while their local fields and rela xations do not. These features and the absence of any critical behavio r are characteristic of a first order F-AF transition, with ferromagne tic domains microscopically identical to the bulk metallic phase of th e OMR manganite. [S0031-9007(98)07678-9].