Origin of the metamagnetic transitions in Y1−Er Fe2(H,D)4.2 compounds

International audienceThe structural and magnetic properties of Y1−xErxFe2 intermetallic compounds and their hydrides and deuteridesY1−xErxFe2H(D)4.2 have been investigated using X-ray diffraction and magnetic measurements under staticand pulsed magnetic field up to 60 T. The intermetallics crystallize in the C15 cubic structure (Fd-3m spacegroup), whereas corresponding hydrides and deuterides crystallize in a monoclinic structure (Pc space group).All compounds display a linear decrease of the unit cell volume versus Er concentration; the hydrides have a0.8% larger cell volume compared to the deuterides with same Er content. They are ferrimagnetic at low fieldand temperature with a compensation point at x=0.33 for the intermetallics and x=0.57 for the hydrides anddeuterides. A sharp first order ferromagnetic-antiferromagnetic (FM-AFM) transition is observed upon heating atTFM−AFM for both hydrides and deuterides. These compounds show two different types of field induced transitions,which have different physical origin. At low temperature (T < 50 K), a forced ferri-ferromagnetic metamagnetictransition with Btrans1 ≈8 T, related to the change of the Er moments orientation from antiparallel toparallel Fe moment, is observed. Btrans1 is not sensitive to Er concentration, temperature and isotope effect. Asecond metamagnetic transition resulting from antiferromagnetic to ferrimagnetic state is also observed. Thetransition field Btrans2 increases linearly versus temperature and relates to the itinerant electron metamagneticbehavior of the Fe sublattice. An onset temperature TM0 is obtained by extrapolating TFM−AFM (B) at zero field.TM0 decreases linearly versus the Er content and is 45 ± 5 K higher for the hydrides compared to the correspondingdeuteride. The evolution of TM0 versus cell volume shows that it cannot be attributed exclusively to apure volume effect and that electronic effects should also be considered