Strain driven monoclinic distortion of ultrathin CoO films in the exchange-coupled CoO/FePt/Pt(001) system

Anne Lamirand (1) , Marcio Soares (1) , Maurizio de Santis (1) , Aline Y. Ramos (2) , Stéphane Grenier (2) , Hélio C. N. Tolentino (3)

1 NEEL - SIN - Surfaces, Interfaces et Nanostructures
2 NEEL - MRS - Matériaux, Rayonnements, Structure
3 NEEL - CRG - CRG & Grands instruments

The structure and strain of ultrathin CoO films grown on a Pt(001) substrate and on a ferro-magnetic FePt pseudomorphic layer on Pt(001) have been determined with insitu and real time surface x-ray diffraction. The films grow epitaxially on both surfaces with an in-plane hexagonal pattern that yields a pseudo-cubic CoO(111) surface. A refined x-ray diffraction analysis reveals a slight monoclinic distortion at RT induced by the anisotropic stress at the interface. The tetrag-onal contribution to the distortion results in a ratio c a > 1, opposite to that found in the low temperature bulk CoO phase. This distortion leads to a stable Co 2+ spin configuration within the plane of the film.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Anne Lamirand, Marcio Soares, Maurizio de Santis, Aline Y. Ramos, Stéphane Grenier, et al.. Strain driven monoclinic distortion of ultrathin CoO films in the exchange-coupled CoO/FePt/Pt(001) system. Journal of Physics: Condensed Matter, 2015, 27 (8), pp.085001. ⟨10.1088/0953-8984/27/8/085001⟩. ⟨hal-01224336⟩