  We present time-of-flight neutron total scattering and polarized neutron
scattering measurements of the magnetically frustrated compounds
NaCaCo$_2$F$_7$ and NaSrCo$_2$F$_7$, which belong to a class of recently
discovered pyrochlore compounds based on transition metals and fluorine. The
magnetic pair distribution function (mPDF) technique is used to analyze and
model the total scattering data in real space. We find that a
previously-proposed model of short-range XY-like correlations with a length
scale of 10-15 \AA, combined with nearest-neighbor collinear antiferromagnetic
correlations, accurately describes the mPDF data at low temperature, confirming
the magnetic ground state in these materials. This model is further verified by
the polarized neutron scattering data. From an analysis of the temperature
dependence of the mPDF and polarized neutron scattering data, we find that
short-range correlations persist on the nearest-neighbor length scale up to 200
K, approximately two orders of magnitude higher than the spin freezing
temperatures of these compounds. These results highlight the opportunity
presented by these new pyrochlore compounds to study the effects of geometric
frustration at relatively high temperatures, while also advancing the mPDF
technique and providing a novel opportunity to investigate a genuinely
short-range-ordered magnetic ground state directly in real space.
