Ferromagnetic resonance in Ni films biased dc sputter deposited on MgO(001)

Abstract

Ferromagnetic resonance measurement at X band is carried out at room temperature to investigate the mechanical and magnetic properties of Ni films 180 nm thick deposited on MgO(001) substrates at 280 °C by biased direct current plasma sputtering at 2.5 kV in Ar gas. A negative bias voltage Vs of 0, −80, and −140 V is applied to the substrate during the deposition. The homogeneous intrinsic stress σi induced in the films is compressive (σi<0) at any Vs and its value is independent of Vs. The magnetic anisotropies due to the anisotropic planar stress σu induced during the film formation and due to the magnetocrystalline anisotropy K1f of the epitaxial Ni crystal are mutually superimposed in the film plane. σu is very weak, i.e., ‖σu‖≪‖σi‖, to reduce nearly to zero as Vs reaches −140 V. Although the magnitude of K1f gradually increases as Vs increases, it is about 10−1 of that of K1 for bulk Ni. The g factor is evaluated at 2.11 independently of Vs.