Effect of absorbed hydrogen on magnetic behavior of Th7Co3 and Th7Ni3

The Pauli paramagnets Th₇Fe₃, Th₇Co₃ and Th₇Ni₃ become superconducting below 1.86 K, 1.83 K and 1.98 K, respectively. These compounds absorb large amounts of hydrogen to form the very hydrogen-rich phases Th₇Fe₃H₃₀, Th₇Co₃H₂₂ and Th₇Ni₃H₂₄. From magnetization studies it is found that hydrogenation results in an increase in the susceptibility of Th₇Co₃, and in a decrease in the susceptibility of Th₇Ni₃, but magnetic ordering is not observed in these two. This is in contrast to the behavior of Th₇Fe₃H₃₀ which is magnetically ordered with a Curie temperature above 350 K.