T. Ebel et al., MAGNETIC-PROPERTIES OF THE URANIUM TRANSITION-METAL CARBIDES U2TC2 (T=RU, OS, RH, IR AND PT), Solid state communications, 97(9), 1996, pp. 815-819
The magnetic susceptibilities of the title compounds were investigated
with a SQUID magnetometer with magnetic flux densities up to 5.5 T in
the temperature range between 2 and 300 K. The carbides U2RuC2 and U2
OsC2 show strong, weakly temperature-dependent paramagnetism, suggesti
ng an intermediate valence for the uranium atoms, while the ruthenium
and osmium atoms do not seem to carry magnetic moments. In contrast, t
he two carbides U2RhC2 and U2IrC2 display temperature-dependent parama
gnetism, which is compatible with one unpaired electron per transition
metal site, while the magnetic susceptibility data of U2PtC2 indicate
two unpaired electrons per formula unit. U2RhC2 exhibits complex magn
etic behaviour below the Neel temperature of T-N = 18(+/-1) K, while t
he temperature dependence of the susceptibility of U2IrC2 resembles th
at of a normal antiferromagnet with T-N = 7(+/-3) K. The presence of t
wo unpaired spins per formula unit in U2PtC2 is remarkable, because th
is carbide is known as a ''nearly-heavy-fermion'' compound, which beco
mes superconducting below 1.5 K.