Disclosing the Nature of Asymmetric Interface Magnetism in Co/Pt Multilayers

Abstract

Nowadays, a wide number of applications based on magnetic materials rely on the properties arising at the interface between different layers in complex heterostructures engineered at the nanoscale. In ferromagnetic/heavy metal multilayers, such as the [Co/Pt] N and [Co/Pd] N systems, the magnetic proximity effect was demonstrated to be asymmetric, thus inducing a magnetic moment on the Pt (Pd) layer that is typically higher at the top Co/Pt­(Pd) interface. In this work, advanced spectroscopic and imaging techniques were combined with theoretical approaches to clarify the origin of this asymmetry both in Co/Pt trilayers and, for the first time, in multilayer systems that are more relevant for practical applications. The different magnetic moment induced at the Co/Pt interfaces was correlated to the microstructural features that are in turn affected by the growth processes that induce a different intermixing during the film deposition, thus influencing the interface magnetic profile.

Gd Doping at the Co/Pt Interfaces to Induce Ultrafast All-Optical Switching

“…As this value is much higher than the magnetization of bulk Co (1420 kA m –1 ), this measurement highlights the contribution of the Pt-induced magnetic moment parallel to the Co-sublattice. Moreover, a value very close to our Ms of 1700 ± 50 kA m –1 has been reported recently by Verna et al in the Pt (3 nm)/Co (0.6 nm)/Pt (3 nm) trilayer deposited on the Ta (3 nm) buffer. This similarity between these two magnetizations demonstrates the very low contribution of Gd to the net magnetization and consequently confirms the low concentration of Gd within the sample .…”

Thin-Film Heterostructures Based on Co/Ni Synthetic Antiferromagnets on Polymer Tapes: Toward Sustainable Flexible Spintronics

“…A successful application of this model was recently demonstrated to disclose the nature of asymmetric interface magnetism in Pt/Co/Pt trilayers and Co/Pt multilayers. 69 To roughly estimate the value of σ expected when Pt, Pd, and Cu are in contact with the top Co layer of the Co/Ni system, we applied the relation 65 A 1 0, 59 1 e B( )…”

“…Furthermore, for a given set of interfaced atoms, the effective interface width (σ) also depends on the stacking order. A successful application of this model was recently demonstrated to disclose the nature of asymmetric interface magnetism in Pt/Co/Pt trilayers and Co/Pt multilayers . To roughly estimate the value of σ expected when Pt, Pd, and Cu are in contact with the top Co layer of the Co/Ni system, we applied the relation σ = 1 0 , 59 A × [ 1 + e − B false( γ normals − γ normalg false) ] where γ s and γ g are the surface energies of the substrate and the growing metals , respectively (considering γ(Co) = 1.27 eV/atom, γ(Cu) = 0.94 eV/atom, γ(Pd) = 1.23 eV/atom γ(Pt) = 1.51 eV/atom), , and A and B are two effective parameters accounting for the exchange mechanisms (ballistic and thermodynamically driven) that were experimentally demonstrated to be mainly dependent on the crystal structure of the substrate and the growing layer (A = 0.27 ± 0.02 nm; B = 1.3 ± 0.5 eV –1 ) …”

Synthesis of highly ordered L10 MPt alloys (M = Fe, Co, Ni) from crystalline salts: an in situ study of the pre-ordered precursor reduction strategy

“…19,20,[22][23][24] Among the family members, chemically ordered binary alloys are of significant interest due to their peculiar atomic arrangement, which results in unique and sometimes remarkable magnetic properties along with excellent chemical stability. 25 Paramount examples of chemically ordered compounds include: (i) Fe(Co)-Pt and Fe(Co)-Pd ferromagnetic alloys for data storage/processing and catalysis, which feature a huge uniaxial magnetic anisotropy (K = 0.5-1 Â 10 7 J m À3 ) 26 that can be intrinsically obtained without resorting to complex multilayered structures; [27][28][29] (ii) high-anisotropy Mn-Al and Fe-Ni alloys (K = 1-2 Â 10 6 J m À3 ) 30 that are cost-effective alternatives to materials containing critical elements for the development of sustainable permanent magnets and electronics; and (iii) antiferromagnetic alloys (e.g., Mn-Pt and Mn-Ni) for spintronic devices. 31 According to the bulk equilibrium phase diagram, [32][33][34][35] around the equiatomic composition, the chemically ordered L1 0 phase, consisting of planes of pure atoms alternating along the c-axis of the face-centered tetragonal (fct) unit cell (ESI, † Fig.…”