Polarized neutron diffraction study of the ferromagnetic semiconductor Yb14MnSb11

Xin (Tony) Tong Indiana University

Our study focuses on transmission neutron spin filters based on polarized 3He and its applications. Polarized 3He is usually produced offsite using spin exchange optical pumping (SEOP) method. Here we report an onsite SEOP 3He pumping system which successfully polarizes 3He while placed in a neutron beam line. It produced polarized 3He with polarization up to 69%. This system is also embedded in an adiabatic fast passage (AFP) nuclear resonance (NMR) device which flips 3He spin axis with nearly no polarization loss. By installing this system at the Single Crystal Diffractometer instrument at IPNS, we performed a polarized neutron diffraction study on magnetic sample Yb14MnSb11. Of our particular interest is the distribution of the spin density in the unit cell, where a Mn2+ (d5) configuration with the moment compensated by the antialligned spin of an Sb 5p hole is expected.

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