The magnetic properties and the possible interaction mechanisms of anisotropic soft- and hard-magnetic multilayers have been investigated by altering the thickness of different kinds of spacer layers. The metal Ta and the insulating oxides MgO, Cr2O3 have been chosen as spacer layers to investigate the characteristics of the interactions between soft- and hard-magnetic layers in the anisotropic Nd-Dy-Fe-Co-B/α-Fe multilayer system. The dipolar and exchange interaction between hard and soft phases are evaluated with the help of the first order reversal curve method. The onset of the nucleation field and the magnetization reversal by domain wall movement are also evident from the first-order-reversal-curve measurements. Reversible/irreversible distributions reveal the natures of the soft- and hard-magnetic components. Incoherent switching fields are observed and the calculations show the semiquantitative contributions of hard and soft components to the system. An antiferromagnetic spacer layer will weaken the interaction between ferromagnetic layers and the effective interaction length decreases. As a consequence, the dipolar magnetostatic interaction may play an important role in the long-range interaction in anisotropic multilayer magnets.

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We report a direct observation of magnetic domain evolution near the Verwey transition (T V ) in Fe 3 O 4 films. We found the stripe domains in the Fe 3 O 4 /Mg 2 TiO 4 film while the irregular domains in the Fe 3 O 4 /MgO film and the similar characters of magnetic domains in the vicinity of T V for both samples: the bigger domain size and the higher contrast of the phase signal below T V and the more disordered domain images at T V . Remarkably, the magnetic behaviors can be well understood and the domain-wall energy and the demagnetizing energy can be calculated from the magnetic domains near T V in the Fe 3 O 4 /Mg 2 TiO 4 film. Our work presents a demonstration of the lowtemperature magnetic domains and gives a new perspective to understand the Verwey transition in Fe 3 O 4 thin films. Published by AIP Publishing. https://doi.

The magnetization manipulation by the current-induced spin–orbit torque opens a prospect for energy-efficient spintronic applications. Here, we investigate controllable spin–orbit torques (SOTs) realized by interlayer exchange coupling (IEC) in Pt/Co/Ru/Co/Pt stacks. The interlayer magnetization realignments originate from the competition between itinerant electron diffusion and current-induced spin current relaxation, and it is revealed that the long-ranged interlayer antiparallel orders exist with a Ru spacer thickness of 2.3 nm. The current-induced hysteresis-loop-shift method is used to assess the H z eff/J depending on the different spacer thicknesses. The loop shift distributions are revealed with the H z eff phase diagrams to characterize the difference between FM-IEC and AFM-IEC. Combining with micromagnetic simulations, a possible transition mechanism of H z eff/J is discussed by combining magnetization switching with the in-plane bias field in IEC systems. This work demonstrates that the spin current realigned IEC mechanism can efficiently control the SOTs in both ferromagnetic and antiferromagnetic multilayers.