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More about Ricardo Ferreira

Ricardo Ferreira

Staff Researcher


Ricardo Ferreira received his PhD from Instituto Superior Técnico (IST) in 2008 upon defending his thesis “Ion Beam Deposited Magnetic Spin Tunnel Junctions targeting HDD Read Heads, Non-volatile Memories and Magnetic Field Sensor Applications”. INESC-MN was the host institution during his PhD and also the lab where he conducted his research until joining INL.

Ricardo’s research work started in 1998, still as a non-graduated student, and has always concerned the production of magnetic tunnel junctions and their optimization targeting different applications.

Low RxA MTJs using AlOx barriers for use as HDD read sensors were a large part of the work developed until 2005. TMR values of up to 23% were maintained down to 2-3 Ohm um2, enabling HDD densities above 100 Gb/inch2.

Starting in 2005, Ricardo began working on non-volatile magnetic memories (MRAM) using a thermally assisted switching mechanism (TAS-MRAM). Ricardo participated in the TAS-MRAM European Project which demonstrated the ability to reduce the writing currents of memory cells down to levels compatible with production and the capacity to prevent the increase of the switching current with bit density. The TAS-MRAM project was the 2nd Finalist of the Descartes Prize for Excellent European Research in 2007, awarded by the European Commission.

Magnetic field sensing applications (such as magnetic imaging and detection of magnetically labeled biological molecules) became important since 2006. A noise spectroscopy measurement setup was created for the characterization of magnetoresistive devices. That allowed the optimization of the SNR ratio of these devices which are currently being produced targeting the detection of pT fields at room temperature.

Since 2007, the work of Ricardo has been focused on the production of low RxA MTJs using MgO barriers targeting devices that explore the spin transfer effect, such as nano-oscillators, and their integration with standard CMOS technology. The linearization of full signal MgO MTJs, appropriate for magnetic field sensing in a number of different applications is also an objective.

Selected Publications:

[1] “Optimization and Integration of Magnetoresistive Sensors”, Paulo P. Freitas, Susana Cardoso, Ricardo Ferreira, Verónica R. Martins, André Guedes, Filipe Cardoso, Joana Loureiro, Rita Macedo, Rui C. Chaves and José Pedro Amaral, SPIN, Vol. 0(1), pp. 1-20 (2011)

[2] “Nanofabrication of 30nm devices incorporating low resistance magnetic tunnel junctions”, R.Macedo, J.Borme, R.Ferreira, S.Cardoso, P.P.Freitas, B. Mendis, M. MacKenzie, J.Nanoscience and Nanotechnology, Vol. 10(9), pp. 5951-5957 (2010)

[3] “Detection of 130nm magnetic particles by a portable electronic platform using spin valve and magnetic tunnel junction sensors”, F. A. Cardoso, J. Germano, R. Ferreira, S. Cardoso, V. C. Martins, P. P. Freitas, M. S. Piedade, L. Sousa, J.Appl.Phys., vol.113, pp.07A310-07A312, April 2008.

[4] “Dynamic Thermomagnetic Writing in Tunnel Junction Cells Incorporating Two GeSbTe Thermal Barriers”, R. Ferreira, S. Freitas and P. P. Freitas, IEEE Trans Magn., vol. 42(10), pp. 2718-2720, October 2006

[5] “Tuning of MgO barrier magnetic tunnel junction bias current for pT magnetic field detection”, R.Ferreira, P.Wisniowski, P.P.Freitas, J.Langer, B.Ocker, W.Maass, J.Appl.Phys., vol.99, pp.08K706-08K708, April 2006.