Evolution of static and dynamic magnetic properties of Re/Co/Pt and Pt/Co/Re trilayers with enhanced Dzyaloshinskii-Moriya interaction

• Double wedges Pt/Re( d Re )/Co( d Co )/Pt and Pt/Co( d Co )/Re( d Re )/Pt were grown by MBE. • d Re induced cobalt fcc to hcp transformation. • Reduction of magnetic surface anisotropy after cobalt fcc to hcp transformation. • Sharp dependence of interface Dzyaloshinskii-Morya interaction on d Re . • Magnetic coercivity strongly depends on d Re for Pt/Re/Co/Pt stacks. The influence of Re layer insertion either at the bottom or top interface of epitaxially grown Pt/Co/Pt heterostructures on their static and dynamic magnetic properties is discussed in terms of their crystalline structure. Magnetic properties were studied as a function of both Re and Co layer thicknesses ( d Re and d Co , respectively) in the matrix-like samples with a double-wedge structure, in which the layer thickness gradients were oriented orthogonally. The comprehensive investigations of the changes in coercivity, perpendicular magnetic anisotropy, spin reorientation transition, interfacial Dzyaloshinskii-Moriya interaction (iDMI) and spin wave damping are reported. Two different magnetic phases depending on the Co layer thickness with volume anisotropies (determined without demagnetization term) of K V ∼0.25 (low) and K V ∼0.75 MJ/m 3 (high) were observed. The relation between these phases depends on the stack sequence and thickness of Re inserted layer. For d Re = 0.2 ÷ 0.7 nm deposited as the bottom interface, d Co induced transition at d tr ∼ 2 nm from low to high volume anisotropy phases was observed. Low and high volume anisotropy phases are associated to Co fcc and hcp structural phases. The insertion of half atomic layer of Re had no influence on surface anisotropy but significantly enhanced iDMI above 1 pJ/m and reduced spin wave damping.