High Field Induced Magnetic Transitions In The Y0.7er0.3fe2d4.2 Deuteride

The influence of the partial Er for Ysubstitution on the crystal structure and magnetic properties of YFe2D4.2 has been investigated by high field magnetization and neutron diffraction experiments. Y0.7Er0.3Fe2D4.2 compound crystallizes in the same monoclinic structure as YFe2D4.2 described in P-c (P(1)c(1)) space group with D atoms located in 18 different tetrahedral interstitial sites. A cell volume contraction of 0.6% is observed upon Er substitution, inducing large modification of the magnetic properties. Electronic effect of D insertion as well as lowering of crystal symmetry are important factors determining the magnetic properties of Fe sublattice, which evolves towards more delocalized behavior and modifying the Er-Fe exchange interactions. In the ground state, the Er and Fe moments are arranged ferrimagnetically within the plane perpendicular to the monoclinic b axis and with average moments m(Er) = 6.4(3)mu(B) Er-1 and m(Fe) = 2.0(1)mu(B) Fe-1 at 10 K. Upon heating, m(Er) decreases progressively until T-Er = 55 K. Between 55 K and 75 K, the Fe sublattice undergoes a first-order ferromagnetic-antiferromagnetic (FM-AFM) transition with a cell volume contraction due to the itinerant metamagnetic behavior of one Fe site. In the AFM structure, m(Fe) decreases until the Neel temperature T-N = 125 K. At high field, two different types of field induced transitions are observed. The Er moments become parallel to the Fe one and saturates to the Er3+ free ion value, leading to an unusual field induced FM arrangement at a transition field B-Trans of only 78 kG below 30 K. Then above T-M0 = 66 K, an AFM-FM transition of the Fe sublattice, accompanied by a cell volume increase is observed. B-Trans increases linearly versus temperature and with a larger dB(Trans)/dT slope than for YFe2D4.2. This has been explained by the additional contribution of Er induced moments above B-Trans.