It is shown that the temperature dependence of muSR spectra of some si
mple cubic (NaCl, CsCl, AuCu3 structures) compounds involving rare ear
ths and actinides differs for a 1k which compared to a a 3k spin struc
ture. This allows their distinction. In the 3k structure magnetic pseu
do excitations resulting from phase de locking diffuse slowly (1-5 MHz
).