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Magnetically Enhanced Memristor

Nov 13, 2012 from 11:00 AM to 02:00 PM

Where Aula 3, Dipartimento di Fisica e Astronomia, viale Berti Pichat 6/2

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Dr.Alek Dediu

Information and communication technology (ICT) is calling for solutions enabling lower power consumption, further miniaturization and multifunctionality requiring the development of new device concepts and new materials. A fertile approach to meet such demands is the introduction of the spin degree of freedom into electronics devices, an approach commonly known as spintronics. This already lead to a revolution in the information storage (GMR readheads) in the last decades. Nowadays, the challenge is to bring spintronics also into devices dedicated to logics, communications and storage within the same material technology.

In this context the electric control of the magnetoresistance represents one of the most promising issues enabling both further miniaturization and multifunctional operation of spintronic devices. Likewise, also the electronics community is committed to follow the Moore’s law, and one of the promising approaches is the use of arrays of crossbar memristors capable of information processing and storing (‘stateful’ logic) [1].

Electrically controlled magnetoresistance can be achieved in organic devices combining magnetic bistability [2] and resistance switching effects [3]. In such devices the GMR effect can be turned ON and OFF by a programming bias that sets the device in low or high resistance state respectively.

The magnitude of the GMR depends on the bias history and can be recovered up to the pristine value. We show in detail how these effects give rise to a conceptually new device - magnetically enhanced memristor. The memristor is the newest member of the family of 2-terminal, passive circuit elements. Its defining property is a non-volatile resistance variation (memristance) that is dependent on the history of the applied current or voltage [3].

The control of the GMR through the resistive state allows to turn off and on the GMR effect by putting the device in the high and low resistance state respectively. The effect is bipolar: GMR can be reduced by the application of sufficiently large negative voltage and it can be restored by the application of a sufficiently large positive voltage. Thus, the typical memristor IV curve can be magnetically modulated leading to a device which we call magnetically enhanced memristor (MEM) and which shows intriguing possibilities in logic gate applications.

We will show the experimental realization of a logic gate, AND, notably built with a single MEM device [4].

Concluding, MEM could be operated in memory and logic gate applications merging together spintronics and electronics approaches towards new future device concepts.

[1] Borghetti, J. et al. “Memristive' switches”, Nature 464, 873, 2010

[2] Dediu, V. A. et al. “Spin routes in organic semiconductors”, Nat. Mater. 8, 707, 2009

[3] Prezioso, M., …, V. A. Dediu “Electrically Programmable Magnetoresistance”, Adv. Mater. 23, 1371, 2011

[4] Prezioso, M., …, V. A. Dediu “A Single-Device Universal Logic Gate Based on a Magnetically Enhanced Memristor”, Adv. Mater. 2012, DOI: 10.1002/adma.201202031