MAGNETIC-PROPERTIES OF THE 2-DIMENSIONAL ANTIFERROMAGNETS RFE2O4 (R = Y, ER) AT HIGH-PRESSURE

Pressure dependence of magnetic susceptibilities of YFe2O4 and ErFe2O4 has been measured up to 6 kbar above about 100 K. Two magnetic phase transitions are observed in the temperature region of 200-250 K at ambient pressure for both compounds. The transitions of YFe2O4 are depressed with increasing pressure. Especially the lower transition rapidly decreases in temperature and then disappears at 6 kbar. The transitions of ErFe2O4 show different pressure dependence, that is, the higher transition temperature increases and the lower one decreases with increasing pressure. The depression of the transition temperatures is explained as the volume effect on the first order phase transition, while the pressure dependence of the higher transition in ErFe2O4 is interpreted as the 10/3 law for the volume dependence of superexchange interaction.