On the influence of nuclear spin and of super-exchange on the spin specific heat of cu(nh 4) 2(so 4) 2.6h 2o

Abstract

Synopsis It is wellknown that the specific heat of the spin system of most cupric salts is much higher than can be explained by magnetic interaction alone. This is generally thought to be due to super-exchange interaction. Since the Cu-nuclei carry a magnetic moment it has to be expected that interaction with the electronic spin of the ion will cause a small splitting, which will also contribute to the specific heat of the spin system. The magnitude of this effect has been determined in the case of Cu(NH 4 ) 2 (SO 4 .6H 2 O by comparing paramagnetic relaxation measurements on this salt with results obtained with a magnetically diluted isomorphous double-salt (5% Cu ++ , 95%Mg + + ).