  We have grown RFe2Ge2 single crystals for R = Y and ten members of the
lanthanide series (Pr, Nd, Sm, Gd-Tm, Lu) using Sn flux as the solvent. The
method yields clean, high quality crystal plates as evidenced by residual
resistivities and RRR values in the range of 3-12 uOhm cm and 20-90
respectively. The crystals are also virtually free of magnetic impurities or
secondary phases, allowing the study of the intrinsic anisotropic magnetic
behavior of each compound. Characterization was made with X-Ray diffraction,
and temperature and field dependent magnetization, specific heat and
resistivity. Very strong anisotropies arising mostly from CEF effects were
observed for all magnetic rare earths except Gd. Antiferromagnetic ordering
occurred at temperatures between 16.5 K (Nd) and 1.1 K (Ho) that roughly scale
with the de Gennes factor for the heavy rare earths. For some members there is
also a lower temperature transition associated with changes in the magnetic
structure. Tm did not order down to 0.4 K, and appears to be a van Vleck
paramagnet. All members which ordered above 2 K showed a metamagnetic
transition at 2 K for fields below 70 kOe. The calculated effective moments per
rare earth atom are close to the expected free ion values of R^3+ except for Sm
which displays anomalous behavior in the paramagnetic state. The non-magnetic
members of this series (Y, Lu) are characterized by an unusually large
electronic specific heat coefficient (gamma ~ 60 mJ/mol K^2) and
temperature-independent susceptibility term (chi_0 ~ 0.003 emu/mol), indicative
of a relatively large density of states at the Fermi surface.
