Spin tunnelling phenomena in single-crystal magnetic tunnel junction systems

• Published in: Journal of physics. Condensed matter 2007-04, Vol.19 (16), p.165201-165201 (35)
• Main Authors: Tiusan, C, Greullet, F, Hehn, M, Montaigne, F, Andrieu, S, Schuhl, A
• Format: Article
• Language: English
• Subjects: Physics
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/19/16/165201

A brief theoretical review points out the specific aspects of electronic transport in single-crystal magnetic tunnel junctions employing bcc(100) Fe electrodes and a MgO(100) insulating barrier. The theoretical predictions are compared to the experimental reality in both equilibrium and out-of-equilibrium regimes. For extremely small MgO thickness, we illustrate that the equilibrium tunnel transport in Fe/MgO/Fe systems leads to antiferromagnetic interactions. Artificial antiferromagnetic systems based on coupling by spin polarized tunnelling have been elaborated and studied. In the out-of-equilibrium regime and for large MgO barrier thickness, the tunnel transport validates specific spin filtering effects in terms of symmetry of the electronic Bloch function and symmetry-dependent wavefunction attenuation in the single-crystal barrier. Within this framework, we explain the experimental giant tunnel magnetoresistive effects at room temperature, up to 180%, measured in our simple or double barrier tunnel junction systems. Moreover, we illustrate that the magneto-transport properties of the junctions may be skilfully engineered by adjusting the interfacial chemical and electronic structure.