PRESENT STATUS OF FERROMAGNETIC THEORY 



71 



thirty years ago on the assumption that the elementary magnets, 

 when they are disturbed by temperature agitation, can assume any 

 orientation. If it be assumed, on the contrary, that the spinning 

 electrons responsible for ferromagnetism can assume only two orienta- 

 tions with respect to the other electrons in the atom, the upper curve is 

 the result. If we assume that four orientations are possible the 

 calculated curve lies close to the upper curve of Fig. 6, but somewhat 



0.8 



CD 0.4 



0.3 



0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 



J_ 



e 



Fig. 6 — Dependence on temperature of the saturation magnetization of iron, cobalt, 



and nickel. 



below it, and as the number of possible orientations is increased the 

 curve approaches the lower one shown in the same figure. The close 

 agreement between the data and the upper calculated curve is of 

 special interest because the spectroscopists and atomic structure 

 experts have come independently, each group from its own data, to the 

 conclusion that each electron in an atom can assume only a small 

 number of orientations with respect to the rest of the atom. 



