Anisotropic magnetic switching along hard [1 1 0]-type axes in Er-doped DyFe2/YFe2 thin films

Abstract Epitaxial-grown DyFe 2 /YFe 2 multilayer thin films form an ideal model system for the study of magnetic exchange springs. Here the DyFe 2 (YFe 2 ) layers are magnetically hard (soft). In the presence of a magnetic field, exchange springs form in the YFe 2 layers. Recently, it has been demonstrated that placing small amounts of Er into the centre of the YFe 2 springs generates substantial changes in magnetic behavior. In particular, ( i ) the number of exchange-spring states is increased dramatically, ( ii ) the resulting domain-wall states cannot simply be described as either Neel or Bloch walls, ( iii ) the Er and Dy magnetic loops are strikingly different, and ( iv ) it is possible to engineer Er-induced magnetic exchange-spring collapse. Here, results are presented for Er-doped (1 1 0)-oriented DyFe 2 (60 A/YFe 2 (240 A) 15 multilayer films, at 100 K in fields of up to 12 T. In particular, we contrast magnetic loops for fields applied along seemingly equivalent hard-magnetic [1 1 0]-type axes. MBE-grown cubic Laves thin films offer the unique feature of allowing to apply the magnetic field along ( i ) a hard out-of-plane [1 1 0]-axis (the growth axis) and ( ii ) a similar hard in-plane [ 1 ¯ 10 ] -axis. Differences are found and attributed to the competition between the crystal-field interaction at the Er site and the long-range dipole-dipole interaction. In particular, the out-of-plane [1 1 0] Er results show the existence of a new magnetic exchange spring state, which would be very difficult to identify without the aid of element-specific technique of X-ray magnetic circular dichroism (XMCD).