  We report on the new compound UCu${}_9$Sn${}_4$ which crystallizes in the
tetragonal structure \emph{I}4/\emph{mcm} with lattice parameters $a =
8.600{\rm\AA}$ and $c = 12.359{\rm\AA}$. This compound is isotyp to the
ferromagnetic systems RECu${}_9$Sn${}_4$ (RE = Ce, Pr, Nd) with Curie
temperatures $T{}\rm_C$ = 5.5 K, 10.5 K and 15 K, respectively.
UCu${}_9$Sn${}_4$ exhibits an uncommon magnetic behavior resulting in three
different electronic phase transitions. Below 105 K the sample undergoes a
valence transition accompanied by an entropy change of 0.5 Rln2. At 32 K a
small hump in the specific heat and a flattening out in the susceptibility
curve probably indicate the onset of helical spin order. To lower temperatures
a second transition to antiferromagnetic ordering occurs which develops a small
ferromagnetic contribution on lowering the temperature further. These results
are strongly hinting for canted antiferromagnetism in UCu${}_9$Sn${}_4$.

Strongly Correlated Electrons