Co2FeAl Heusler thin films grown on Si and MgO substrates: annealing temperature effect

Abstract

10 nm and 50 nm Co${}_2$FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to the relation CFA(001)[110]//MgO(001)[100] epitaxial relation), respectively for CFA films grown on a Si and on a MgO substrate. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (Ta) while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and of a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing Ta while the uniaxial anisotropy field is nearly unaffected by Ta within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with $T_a$. Finally, the FMR linewidth decreases when increasing Ta, due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.3*10^-3 and 1.1*10^-3 for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively).

8 pages, 7 figures to appear in J. App. Phys

References in corpus (2)

• Calculated electronic and magnetic properties of the half-metallic, transition metal based Heusler compounds
• Low relaxation rate in a low-Z alloy of iron

Cited by in corpus (6)

• Temperature-dependent Gilbert damping of Co2FeAl thin films with different degree of atomic order
• Uniaxial anisotropy, intrinsic and extrinsic damping in Co${}_2$FeSi Heusler alloy thin films
• First principles studies of the Gilbert damping and exchange interactions for half-metallic Heuslers alloys
• Thickness-dependence of the Dzyaloshinskii-Moriya interaction in Co2FeAl ultrathin films: effects of the annealing temperature and the heavy metal material
• Observation of Skyrmions at Room Temperature in Co2FeAl Heusler Alloy Ultrathin Films
• Investigation of the interfacial Dzyaloshinskii-Moriya interaction sign in Ir/Co2FeAl systems by Brillouin light scattering