EFFECT OF HE4 ON EXCHANGE IN HCP SOLID HE3

NMR measurements of the exchange-lattice relaxation time of h.c.p. solid He3 containing He4 impurity atoms show two time-constants. The frequency and temperature dependence of the first time-constant is characteristic of pure He3. The second time-constant is associated with impurity He4 atoms and may be analysed to give an average increased exchange parameter, as well as the number of He3 atoms influenced by each He4. A model previously proposed for b.c.c. He3 can be used to explain these results, but certain inadequacies appear. © 1969.