XMCD characterization of the ferromagnetic state of Yb₁₄MnSb₁₁

X-ray magnetic circular dichroism (XMCD) measurements on Yb₁₄MnSb₁₁ provide experimental evidence of a moment of 5 μ_B on Mn, with partial cancellation by an opposing moment on the Sb4 cage surrounding each Mn ion. The compound is isostructural to Ca₁₄AISb₁₁, with Mn occupying the AI site in the AISb₄ ^9- discrete tetrahedral, anionic unit. Bulk magnetization measurements indicate a saturation moment of 3.90 ± 0.02 μ_B/formula unit consistent with four unpaired spins and implying a Mn³⁺, high-spin d4 state. XMCD measurements reveal that there is strong dichroism in the Mn L₂₃ edge, the Sb M₄₅ edge shows a weak dichroism indicating antialignment to the Mn, and the Yb N₄₅ edge shows no dichroism. Comparisons of the Mn spectra with theoretical models for Mn²⁺ show excellent agreement. The bulk magnetization can be understood as Mn with a moment of 5 μ_B and a 2+ configuration, with cancellation of one spin by an antialigned moment from the Sb 5p band of the Sb₄ cage surrounding the Mn.