Abstract
The effect of hydrogenation on magnetic properties of weakly ferromagnetic superconductor UCoGe was studied. UCoGe hydrides were synthesized at T = 773 K at different pressure of H2 gas (8, 5, 2 bar).
The hydrogenation at 8 bar and 5 bar results in the change of the crystal structure from the orthorhombic (TiNiSi structure type) to the hexagonal (ZrBeSi type) giving H concentration little below 2 H at./f.u. For one of such b-hydrides, UCoGeH1.7, the Curie temperature increases from 3 K up to 50 K and the spontaneous magnetic moment from 0.03 mB/f.u. to 0.05 mB/f.u.
An a-hydride of UCoGe (DV/V = 0.25 %) with the hydrogen concentration 0.1 H/f.u. was obtained at 2 bar. It has the same type of crystal structure as a pure compound and surprisingly exhibits no magnetic order.