Antiferromagnetic Structure ofα-Manganese and a Magnetic Structure Study ofβ-Manganese

Neutron diffraction data have been obtained at 4.2\ifmmode^\circ\else\textdegree\fi{}K and 298\ifmmode^\circ\else\textdegree\fi{}K for both $\ensuremath{\alpha}$-Mn and $\ensuremath{\beta}$-Mn. The pattern of moment alignment in the antiferromagnetic state of $\ensuremath{\alpha}$-Mn is deduced. Dependent on interatomic distance, both parallel and antiparallel spin couplings are present. Also, for one kind of atom no moment alignment occurs. The magnitudes of the individual moments appear to exceed considerably one Bohr magneton. No coherent magnetic scattering is detectable for $\ensuremath{\beta}$-Mn at 4.2\ifmmode^\circ\else\textdegree\fi{}K. The effect of atomic separation and of atomic arrangement on magnetic structure is discussed.