THE PHYSICAL BASIS OF FERROMAGNETISM 



25 



_R_ _ ATOMIC SEPARATION 

 r ~ DIAMETER OF 3d ORBIT 



Fig. 14 — Bethe's curve relating the energy of magnetization to the distance be- 

 tween atom-centers, with a fixed diameter of the unfilled inner shell that has the 

 magnetic moment. 



ferromagnetic elements than in other elements having incomplete inner 

 shells, and that the point at which the curve crosses from the non- 

 ferromagnetic to the ferromagnetic region is near Rjr =1.5. Values 

 of 2i?, Ir and Rjr, as calculated by Slater for some of the elements 

 with incomplete inner shells, are given in Table II. 



TABLE II 



Internuclear Distances (2i?) and Diameters (2r) of Incomplete 

 Inner Shells of Some Atoms, in Angstroms 



Calculated using Slater's formula. 



