WEAK FERROMAGNETIC-RESONANCE OF GD2CUO4 SMALL PARTICLES

Microwave-absorption measurements have been performed in Gd2CuO4 parti cles of controlled size. We have measured the microwave absorption ass ociated with a magnetic resonance of the weak-ferromagnetic component of the magnetization. The onset temperature of this signal, related to the appearance of weak ferromagnetism, is depressed when the particle size is decreased. A simultaneous depression of the Neel temperature is suggested as the origin of the observed dependence, due to the limi tation on the two-dimensional correlation length imposed by the partic le size. (C) 1996 American Institute of Physics.