Growth, structure and thermal stability of quasicrystalline Al–Pd–Mn–Ga thin films

Abstract

Growth of Al–Pd–Mn–Ga quasicrystalline thin film is hindered by the low melting temperature of Ga (30 °C) and the formation of residual binary phases. In this study, a stable icosahedral film with a composition near Al67.5Pd19Mn7.5Ga5.7 has been achieved using the co-sputtering of Al64.9Pd20.7Mn8.4Ga6 and Al materials followed by ex-situ annealing. The increase in the 6d lattice parameter from 6.45 to 6.48 Å of icosahedral phases suggested that Ga (+1) successfully replaced Al(+3) in the composition. The temperature-dependent XRD study (from RT to 700 °C) reveals that the icosahedral phase found only in a narrow temperature window of 350 – 450 °C. Interestingly, Al63Pd18Mn7.5Ga6 quasicrystalline thin film exhibits cluster spin glass behaviour due to spin-spin interaction of localized Mn ions. These stable icosahedral thin films with crack-free well-defined surfaces can be useful for potential surface-related applications. © 2019 Elsevier B.V.