Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 27: Spin currents and spin torques
MA 27.10: Vortrag
Mittwoch, 14. März 2018, 12:00–12:15, EB 407
Ab-initio study on L10 FePt-based magnetic tunnel junctions for memory applications — •Mario Galante, Matthew O. A. Ellis, and Stefano Sanvito — School of Physics, Trinity College Dublin, Ireland
Magnetic random access memory (MRAM) is believed to be one of the most promising candidates for the future of scalable non-volatile memories. At the heart of these devices are magnetic tunnel junctions (MTJs), which store data on the relative orientation of two magnetic layers separated by an insulating barrier and can be operated via electric currents exploiting the tunnelling magneto-resistance (TMR) and the spin-transfer torque (STT) effects. Junctions with out-of-plane magnetisation minimise the demagnetising field contribution to the switching current but a large magneto-crystalline anisotropy is required to keep such geometries. Common CoFeB/MgO devices have been shown to have a suitable anisotropy due to interface effects [1] but materials with large bulk anisotropy, such as L10-FePt, are also possible candidates. In this work, we have applied the SMEAGOL method [2] for ab-initio quantum transport to Fe/MgO/Fe MTJs with a L10-FePt layer inserted at the MgO-free layer interface. We investigate the suitability of FePt-based MTJs for memory applications by calculating the atom-resolved spin torque and the TMR in comparison with a Fe/MgO/Fe junction. We also consider the presence of a thin Fe seed layer and discuss how this influences the decay of the STT in the free layer. [1] A. Hallal, et al, PRB 88, 184423 (2013) [2] A. R. Rocha et al, PRB 73, 085414 (2006)