Magnetic properties of the hydrogenated unconventional superconductor UCoGe–H

Abstract

Abstract The effect of hydrogenation on magnetic properties of the 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 a change of the crystal structure from orthorhombic (TiNiSi structure type) to hexagonal (ZrBeSi type) with H concentrations just below 2 H/f. u. For one of such β-hydrides, UCoGeH1.7, the Curie temperature increases from 3 K up to 50 K and the spontaneous magnetic moment from 0.03 μB/f. u. to 0.05 μB/f. u. An α-hydride of UCoGe (ΔV/V = 0.25 %) with a hydrogen concentration 0.1 H/f. u. was obtained at 2 bar. It has the same crystal structure as a pure compound and surprisingly exhibits no magnetic order.