Cu2MnAl thin films grown onto sapphire and MgO substrates: Exchange stiffness and magnetic anisotropy



Cu2MnAl films of different thicknesses (50, 70, and 100 nm) were grown by UHV RF-sputtering on a-plane sapphire or on MgO (100) substrates. Their structural and static magnetic properties have been studied by X-rays diffraction (XRD) and by vibrating sample magnetometry (VSM), respectively. The Cu2MnAl films exhibit a (100) and (110)-texture when grown on MgO and sapphire substrates, respectively. The best growth quality and the higher magnetization at saturation were obtained for the films grown on MgO. Dynamic magnetic properties were investigated using micro-strip line ferromagnetic resonance (MS-FMR). From the resonance measurements varying the direction and the amplitude of the in-plane and out-of-plane applied magnetic fields we derive the effective magnetization, the Landé g-factor (g = 2.11), the exchange constant (Aex = 0.34 µerg cm−1) and the magnetic anisotropy terms. The in-plane anisotropy can be described as a superposition of two terms showing a small twofold and a dominant fourfold symmetry.