Preparation and magnetic properties of the CoO/Co bilayer

                B. Raquet a, R. Mamy a*, J.C. Ousset a, N. Nègre a, M. Goiran a and C. Guerret-Piécourt b

 aLaboratoire de Physique de la Matière Condensée de Toulouse, INSA. SNCMP, Universite Paul sabatier, Complexe Scientifique
                                       de Rangueil, 31077 Toulouse Cedex 4, France
                           bLAAS-CNRS, 7 av. du Colonel Roche, 31077 Toulouse Cedex, France

                             Received 28 July 1997; Received in revised form 7 November 1997



Abstract

The results of the preparation, characterization and magnetic properties of a CoO/Co interface are discussed. This interface was
realized by ultraviolet irradiation of a 4nm Co layer deposited with a gold buffer layer on a GaAs(111) substrate. The Co oxide
analyzed by XPS and AFM revealed a continuous 1.7nm thick layer with a rms roughness of 0.6nm and mostly CoO at the
interface. Longitudinal magneto-optical Kerr loops evidence a strong initial in-plane anisotropy which disappears on oxidation.
Values of the unidirectional exchange coupling at the Co/CoO interface were obtained: 0.1erg/cm2 from SQUID measurement at
5K after field cooling and 0.6erg/cm2 with magneto-optical Kerr effect in polar configuration from modelization of the M(H) curve.
This discrepancy is discussed in terms of the difference of sensing the interfacial coupling in the two cases due to atomic steps.

PACS classification codes 75-60; 75-70; 81-15G

Keywords: Exchange coupling; Anisotropy - uniaxial; Anisotropy - unidirectional; Thin films


*Corresponding author. Tel.: +33 5 61 55 61 85; e-mail: mamy@insa-tlse.fr.