ANTIFERROMAGNETISM IN CU(NH3)4SO4.H2O

The magnetic structure of the magnetic linear chain substance, Cu(NH3)4SO4‧H2O, has been investigated by means of proton nuclear magnetic resonance and magnetic susceptibility measurements. A transition from the short range (or intra-chain) ordered state to the long range ordered state was found at 0.43±0.01°K in both measurements. The magnetic spin arrangement inferred from the rotation studies of the proton N. M. R. is nearly antiferromagnetic in a -O-Cu-O-Cu-O- chain, and nearly parallel to the oaxis. It is plausible that spins cant by few degrees from the direction parallel to the c-axis. This spin structure is inconsistent with the previous magnetic susceptibility data by Haseda and Miedema. Therefore, susceptibility measurements have been repeated taking care of the thermal equilibrium between the sample and the cooling agent in the temperature region between 4.25 and 0.03°K, and the results different from their work have been obtained, which are not inconsistent with the spin structure inferred from the proton N. M. R. © 1969, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.