抄録
Single crystals of K2CuCl4·2H2O and (NH4)2CuCl4·2H2O were examined at 7 different frequencies of microwaves (from 5.4 mm to 6.2 cm wave-lengths). If there were no exchange coupling, two absorption peaks would be expected corresponding to different g-values of two dissimilar Cu++ ions in unit cell. Experimentally, however, only one peak can be observed at, longer wave-lengths, though the line width remarkably increases with decreasing wavelengths. At the wave-length of 5.4 mm two isolated peaks can be observed. These facts can be interpreted in terms of exchange interaction between dissimilar ions. The exchange energy estimated from these data is greater than 0.1 cm−1. On the other hand, the width for the c-axis, where the situations of two Cu++ groups are identical, decreases with decreasing wave-lengths to aboutthe value 1/4 of that at long enough wave-length. According to the treatment by Anderson and Weiss, this result may be explained by their “10/3” effect.
