Influence of the growth conditions on the magnetism of SrFe₁₂O₁₉ thin films and the behavior of Co/SrFe₁₂O₁₉ bilayers

Abstract

SrFe12O19 (SFO) films grown on Si (100) substrates by radio-frequency magnetron sputtering have been characterized in terms of composition, structural and magnetic properties by a combination of microscopy, diffraction and spectroscopy techniques. Mössbauer spectroscopy was used to determine the orientation of the films magnetization, which was found to be controlled by both the sputtering power and the thickness of the films. Additionally, the coupling between the SFO films and a deposited cobalt overlayer was studied by means of synchrotron-based spectromicroscopy techniques. A structural coupling at the SFO/Co interface is suggested to account for the expetimental observations. Micromagnetic simulations were performed in order to reproduce the experimental behaviour of the system.

Uncorrelated magnetic domains in decoupled SrFe12O19/Co hard/soft bilayers

“…In addition, simulations strongly suggest that there is an absence of interlayer exchange-coupling, as they predict that even coupling values as low as κ = 0.1 should lead to a certain alignment of soft spins with the hard layer. We have followed up the study of the magneto-dipolar coupling in bilayer thin films by using hard layers with in plane magnetization, so that the competition with the strong influence of the soft layer shape anisotropy is avoided [24].…”

“…In an earlier work by our group, strontium ferrite (SrFe 12 O 19, SFO)/Co thin-film bilayers were investigated [24]. In that system, the continuous SFO film under study was magnetized in-plane.…”

Unraveling Exchange Coupling in Ferrites Nano‐Heterostructures

“…Our nano-heterostructures are the result of the high control of interface epitaxy achieved through controlled annealing, which produces a [100]// [1][2][3][4][5][6][7][8][9][10] texture between SFO and CFO induced by the (111) of preformed CFO (as depicted in Figure 6c, together with a schematic of the reversal). Knowing that the easy axes are not parallel to each other (while the SFO core has an out-of-plane easy axis, the CFO layer tends to lie along the [100] axis) [60,61] induce to believe that the strong coupling is not due to dipolar interaction between the two materials, as it may be the case for such misinterpretation if the easy axes were aligned. In contrast, the physically mixed systems (with similar size as in NC_1) for which we do not expect any exchange-coupling, show an agreement with the superposition of the members, even when the two phases are in closer contact (by applying pressure) thus expecting higher dipolar interactions (as previously shown in Figure S12, Supporting Information).…”