Magnetism in Molybdate Pyrochlores

Pyrochlores are compounds with the generic stoichiometry A₂B₂O₇ and the crystal space group Fm-3m.  Magnetic pyrochlores are currently heavily researched as the forces between the magnetic ions they contain compete with one another, leading to magnetic 'frustration' and a large variety of exotic magnetic behaviour.  The magnetism can be better described by mean-field or 'classical' theories if the moments are larger, but quantum physics - a subject of great current interest - is necessary of the moments become very small.  
Experiments on samples with small moments is very difficult because the magnetic signal is small and can be easily lost in scattering from other contributions.  By using polarization analysis, D7 is able to separate small magnetic signals, making it remarkably sensitive.  In the example here, the authors wished to observe the magnetic scattering from powdered samples of the small-moment pyrochlores Lu₂Mo₂O₇ and Lu₂Mo₂O₅N₂.  The data show that D7 can observe scattering from 0.11 μ_B per formula unit, or 0.055 μ_B per Mo ion.

Ref: L. Clark, G. J. Nilsen, E. Kermarrec, G. Ehlers, K. S. Knight, A. Harrison, J. P. Attfield, and B. D. Gaulin, Phys. Rev. Lett. 113 117201, (2014)