Influence of the surface chemistry on the electric-field control of the magnetization of ultrathin films

In this paper we investigate the voltage dependence of magnetization anisotropy on electrodeposited Co/Au(111) ultrathin films using in situ real-time polar magneto-optical Kerr effect. A systematic voltage and thickness-dependent study is conducted, demonstrating that the magnetoelectric effects arise from an electric field-induced change in the surface anisotropy. The effect is linear, reversible, and can be as large as 50%. We also show that its amplitude depends on the surface chemistry of the Co films. Another kind of magnetoelectric is also reported and discussed that allows a reversible and complete spin reorientation transition in a 5.6-monolayer-thick layer covered with carbon monoxide.