Yu. V. Pershin

Spin memristive systems : Spin memory effects in semiconductor spintronics

Recently, in addition to the well-known resistor, capacitor, and inductor, a fourth passive circuit element, named memristor, has been identified following theoretical predictions. The model example used in such case consisted in a nanoscale system with coupled ionic and electronic transport. Here, we discuss a system whose memristive behavior is based entirely on the electron-spin degree of freedom, which allows for a more convenient control than the ionic transport in nanostructures. An analysis of time-dependent spin transport at a semiconductor/ferromagnet junction provides a direct evidence of memristive behavior. Our scheme is fundamentally different from previously discussed schemes of memristive systems and broadens the possible range of applications of semiconductor spintronics.

Memristive adaptive filters

Using the memristive properties of vanadium dioxide, we experimentally demonstrate an adaptive filter by placing a memristor into an LC contour. This circuit reacts to the application of select frequency signals by sharpening the quality factor of its resonant response, and thus “learns” according to the input waveform. The proposed circuit employs only analog passive elements, and may find applications in biologically inspired processing and information storage. We also extend the learning-circuit framework mathematically to include memory-reactive elements, such as memcapacitors and meminductors, and show how this expands the functionality of adaptive memory filters.

Putting Memory Into Circuit Elements: Memristors, Memcapacitors, and Meminductors [Point of View]

The memdevices we have defined open up a whole new world of possibilities in electronics and provide us with new tools to study old scientific problems from a new perspective. Due to their recent introduction, it is difficult to say what new applications will be found and which course the field will take from here. Irrespective, we believe the time is ripe for new and exciting innovations in electronics and hope our work will motivate more experimental and theoretical investigations in this direction.

Solid-State Memcapacitive System with Negative and Diverging Capacitance

We suggest a possible realization of a solid-state memory capacitive (memcapacitive) system. Our approach relies on the slow polarization rate of a medium between plates of a regular capacitor. To achieve this goal, we consider a multi-layer structure embedded in a capacitor. The multilayer structure is formed by metallic layers separated by an insulator so that non-linear electronic transport (tunneling) between the layers can occur. The suggested memcapacitor shows hysteretic charge-voltage and capacitance-voltage curves, and both negative and diverging capacitance within certain ranges of the field. This proposal can be easily realized experimentally, and indicates the possibility of information storage in memcapacitive devices.

Emulation of floating memcapacitors and meminductors using current conveyors

Suggested are circuit realisations of emulators transforming memristive devices into effective floating memcapacitive and meminductive systems. The emulators circuits are based on second generation current conveyors and involve either four single-output or two dual-output current conveyors. The equations governing the resulting memcapactive and meminductive systems are presented.

Memory Circuit Elements: From Systems to Applications

In this paper, we briefly review the concept of memory circuit elements, namely memristors, memcapacitors and meminductors, and then discuss some applications by focusing mainly on the first class. We present several examples, their modeling and applications ranging from analog programming to biological systems. Since the phenomena associated with memory are ubiquitous at the nanoscale, we expect the interest in these circuit elements to increase in coming years.

Analogue-to-digital and digital-to-analogue conversion with memristive devices

A novel methodology is suggested to obtain a digital representation of analogue signals and to perform its back-conversion using memristive devices. In the proposed converters, the same memristive systems are used for two purposes: as elements performing conversion and elements storing the code. This approach to conversion is particularly relevant for interfacing analogue signals with memristive digital logic/computing circuits.

Spin polarization control by electric stirring: proposal for a spintronic device

We propose a spintronic device to generate spin polarization in a mesoscopic region by purely electric means. We show that the spin Hall effect in combination with the stirring effect are sufficient to induce measurable spin polarization in a closed geometry. Our device structure does not require the application of magnetic fields, external radiation or ferromagnetic leads, and can be implemented in standard semiconducting materials.