Thermal enhancement of the antiferromagnetic exchange coupling between Fe epilayers separated by a crystalline ZnSe spacer

• Published in: Journal of physics. Condensed matter Vol. 18; no. 39; pp. 9105 - 9118
• Main Authors: Varalda, J, Milano, J, de Oliveira, A J A, Kakuno, E M, Mazzaro, I, Mosca, D H, Steren, L B, Eddrief, M, Marangolo, M, Demaille, D, Etgens, V H
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 04.10.2006; Institute of Physics; IOP Publishing [1989-....]
• Subjects: Condensed Matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance; Interfacial magnetic properties (multilayers, magnetic quantum wells, superlattices, magnetic heterostructures); Magnetic properties and materials; Magnetic properties of surface, thin films and multilayers; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Physics; Defect states; Epitaxial layers; Semiconductor materials; Magnetization; Tunnel effect; Zinc selenides; Iron; Sandwich structures; Thickness; Ferromagnetic resonance; Multilayers; Transition elements; Exchange interactions
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/18/39/036

We provide evidence for the existence of an antiferromagnetic coupling between iron epilayers separated by a wedge-like ZnSe crystalline semiconductor by magnetometric and ferromagnetic resonance experiments. The coupling strength of 46 muJ m(-2) for t(ZnSe) = 25 A(ngstrom) is strongly reduced as the barrier thickness is increased. The coupling increases linearly with temperature from 5 to 300 K, with a 5.5 x 10(-9) J m(-2) K(-1) rate. Thermally induced effective exchange coupling mediated by spin-dependent tunnelling of electrons via localized mid-gap defect states in the ZnSe spacer layer appears to be the most plausible mechanism to induce the antiferromagnetic coupling.