Magnetization studies on Tm2Fe17-xCoxand Tm2Fe17-xAlxcompounds

Magnetization studies were carried out on Tm
2
Fe
17-x
Co
x
and Tm
2
Fe
17-x
Al
x
compounds in the temperature range 4.2 K to 1200 K. Tm
2
Fe
17
changes its easy axis of magnetization from the basal plane to c-axis below 85 K. This transition occurs at higher temperatures as cobalt or aluminum is substituted for iron. The
\underline{c}
lattice parameter goes through a maximum as a function of x in the Tm
2
Fe
17-x
Co
x
ternaries. The results are interpreted in terms of distance dependence of the magnetic interactions and a competition between the sublattice magnetic anisotropy. Tm
2
Fe
3
Co
14
has an anisotropy field of 38 kOe and a potential energy product of 43 MGOe at room temperature.