Resonant magnetic x-ray scattering from mixed-valence TmSe.

The mixed-valent compound TmSe has been studied in its antiferromagnetic state (T <T(N) = 3.2) by resonant magnetic x-ray scattering. The (003) magnetic reflection shows two peaks as a function of incident energy corresponding to the L(III) absorption edges of its Tm2+ and Tm2+ configurations. This unambiguously establishes that long-range magnetic order is present for both valence states. An Anderson impurity model including multiplet and core-hole effects gives a good description of the data.