Anisotrophy of the magnetic properties of the cuprates Dy2BaCuO5 and Ho2BaCuO5: Magnetic and spectroscopic investigations

The magnetization of single crystals of the cuprates Dy2BaCuO5 and Ho2BaCuO5 along different crystallographic directions is measured using a SQUID magnetometer in fields up to 54 kOe. Spectroscopic investigations of the exchange splitting of the levels of Er3+ probe ions in these cuprates are also performed. It is shown that the cuprates investigated are highly anisotropic antiferromagnets, which display quasi-Ising behavior in a magnetic field. The nature of the two spontaneous magnetic phase transitions detected in Dy2BaCuO5 and Ho2BaCuO5 is analyzed. It is shown that the low-temperature transition is due to an increase in rare-earth-copper exchange. (C) 1997 American Institute of Physics.