  The pyrochlore Ho2Ge2O7 is a new highly correlated spin ice material.
Physical property measurements including x-ray diffraction, dc susceptibility
and ac susceptibility, confirm that it shares the distinctive characteristics
of other known spin ices. Polarized neutron scattering measurements on a powder
sample, combined with reverse Monte Carlo (RMC) refinements, give unique
information about the spin ice state in Ho2Ge2O7. RMC refinements are used to
fit the powder magnetic diffuse scattering and predict the single crystal
magnetic scattering of Ho2Ge2O7, demonstrating consistency with spin ice
behavior.
