Origin of the metamagnetic transitions in Y1−xErxFe2(H,D)4.2 compounds

•Two different first order type metamagnetic transitions are observed.•Ferri-ferromagnetic transition with transition field of 8 T is due to Er moment.•A transition due to the IEM behavior of the Fe sublattice is found at TM0.•Transition fields from FM toAFM state increases linearly above TM0.•The variation of TM0 versus Er and (H,D) is not a pure magnetovolume effect. The structural and magnetic properties of Y1−xErxFe2 intermetallic compounds and their hydrides and deuterides Y1−xErxFe2H(D)4.2 have been investigated using X-ray diffraction and magnetic measurements under static and pulsed magnetic field up to 60 T. The intermetallics crystallize in the C15 cubic structure (Fd-3m space group), 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 a 0.8% larger cell volume compared to the deuterides with same Er content. They are ferrimagnetic at low field and temperature with a compensation point at x = 0.33 for the intermetallics and x = 0.57 for the hydrides and deuterides. A sharp first order ferromagnetic-antiferromagnetic (FM-AFM) transition is observed upon heating at TFM−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