1048 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1954 



correct value of Ms for Fe304 at room temperature (475 c.g.s. units) has 

 been used in calculating the jS given in Table I than has been used in 

 previous calculations. 



In Table I we give in addition to values of /3, values of X at room tem- 

 perature obtained from (13). The value for Fe304 is calculated from the 

 new value of /3 and also corrected for the error mentioned in Reference 

 14. Values given in References 7 and 8 are somewhat in error. The A'alues 

 of j3 and X given for Fe304 in Table I are the remainders after the contri- 

 bution due to eddy currents has been subtracted out by means of the 

 low field calculation of Williams, Shockley, and Kittel,^ [see their Equa- 

 tion (11)]. 



Table I — • Room Temperature Data on Fe304 and 

 (NiO)o.75 (FeO)o.25 FezOs 



* The value of Ms at 300°^" is measured from the hysteresis loop of Fig. 3. 

 Other values were obtained by assuming that M^ varied with T in the same wa}- 

 as observed by Weiss and Forrer'' in FcsOi . 



The evaluation of X from (13) is done as follows. Since the wall is in a 

 (110) plane, we find from (10): 



g{e) - cAOo) = L|l! (2/ Vs - V3 sin^ ey, 



(34) 



where d is the angle between M and the [100] direction which Hes in the 

 plane of the domain wall. 6 is cos~^(l/\/3) on one side of the wall, and 



