Physica B 322 (2002) 312–314 Magnetic behavior of Fe(0 0 1)/ZnSe(0 0 1)/Fe(0 0 1) sandwiches grown on ZnSe(0 0 1) epilayer on GaAs(0 0 1) J. Varalda a, *, G.A.P. Ribeiro a , W.A. Ortiz a , A.J A. de Oliveira a , D.H. Mosca b , V.H. Etgens c , M. Eddrief c a Grupo de Supercondutividade e Magnetismo, Centro Multidisciplinar para o Desenvolvimento de Materiais Cer # amicos, Departamento de F! ısica, Universidade Federal de S * ao Carlos, Rodovia Washington Luiz Km 235, Caixa Postal 676, 13565-905 S * ao Carlos, SP, Brazil b Departamento de F! ısica, Universidade Federal do Paran ! a, 81531-990 Curitiba, PR, Brazil c Laboratoire de Min ! eralogie et Crystallographie de Paris, Universit ! e Paris VI et VII, 75252 Paris, France Received 15 March 2002 Abstract The magnetic behavior of the hybrid heterostructures Fe(0 0 1)/ZnSe(0 0 1)/Fe(0 0 1) grown on ZnSe(0 0 1) epilayers on GaAs(0 0 1) substrates by molecular beam epitaxy was investigated by SQUID magnetometry. Three different thicknesses of the ZnSe spacer layer were used to investigate the magnetic coupling between 200 ( A thick Fe layers. Our results indicate the existence of an effective exchange bias field of about 5 Oe possibly originating from a residual antiferromagnetic coupling through 50 ( A thick ZnSe layer. r 2002 Elsevier Science B.V. All rights reserved. PACS: 75.30.Et; 75.70.Ak; 75.70.Cn Keywords: Hybrid heterostructures; Fe films; Fe/ZnSe/Fe trilayers; Exchange coupling 1. Introduction Hybrid ferromagnetic/semiconductor hetero- structures have attracted great interest in view of their potential applications to fabricate spin-based electronic devices. In particular, Fe and ZnSe form a very promising pair of materials due to their high chemical stability, low lattice mismatches and wide band gap to optoelectronics and tunnel-based applications. Recent works have demonstrated that antiferromagnetic exchange coupling could occur in Fe/ZnSe/Fe trilayers with an amorphous ZnSe spacer [1–3]. In this work, we investigate the magnetic behavior of the Fe(0 0 1)/ZnSe(0 0 1)/ Fe(0 0 1) heterostructures epitaxially grown on ZnSe(0 0 1) epilayers on GaAs(0 0 1). The samples have been prepared in a multi- growth molecular beam epitaxy (MBE) chamber. Firstly, a 3000 ( A non-doped GaAs buffer layer was grown on Te-doped GaAs(0 0 1) in standard conditions [4]. Subsequently, the (2 Â 4) b phase [5] was stabilized and the sample was quickly transferred under ultra-high vacuum to the II–VI growth chamber. Undoped ZnSe(0 0 1) epilayers were then grown onto the fresh GaAs(0 0 1) surfaces. The GaAs surface was exposed at 2201C to a Zn overpressure and the growth started *Corresponding author. Fax: +55-16-2614835. E-mail address: pjov@df.ufscar.br (J. Varalda). 0921-4526/02/$ - see front matter r 2002 Elsevier Science B.V. All rights reserved. PII:S0921-4526(02)01199-7