A chiral-based magnetic memory device without a permanent magnet

Oren Ben Dor,Yossi Paltiel,Shira Yochelis,Ron Naaman,Shinto P Mathew

doi:10.1038/ncomms3256

Oren Ben Dor, Yossi Paltiel + Show 3 more

Open Access

https://doi.org/10.1038/ncomms3256

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Abstract

Several technologies are currently in use for computer memory devices. However, there is a need for a universal memory device that has high density, high speed and low power requirements. To this end, various types of magnetic-based technologies with a permanent magnet have been proposed. Recent charge-transfer studies indicate that chiral molecules act as an efficient spin filter. Here we utilize this effect to achieve a proof of concept for a new type of chiral-based magnetic-based Si-compatible universal memory device without a permanent magnet. More specifically, we use spin-selective charge transfer through a self-assembled monolayer of polyalanine to magnetize a Ni layer. This magnitude of magnetization corresponds to applying an external magnetic field of 0.4 T to the Ni layer. The readout is achieved using low currents. The presented technology has the potential to overcome the limitations of other magnetic-based memory technologies to allow fabricating inexpensive, high-density universal memory-on-chip devices.

Highlights

Several technologies are currently in use for computer memory devices
If the free layer and the permanent magnet are aligned in parallel, the resistivity of the device is lower than when they are aligned antiparallel to each other
Because in the present configuration the spin of the transferred electrons through the layer is polarized parallel to their velocity, magnetization is induced in the layer perpendicular to its surface

Summary

Introduction

There is a need for a universal memory device that has high density, high speed and low power requirements To this end, various types of magnetic-based technologies with a permanent magnet have been proposed. Recent charge-transfer studies indicate that chiral molecules act as an efficient spin filter We utilize this effect to achieve a proof of concept for a new type of chiral-based magnetic-based Si-compatible universal memory device without a permanent magnet. In spin-transfer torque memory, the device looks very similar, but here the magnetization of the ferromagnetic free layer is determined by transferring spin alignment to it, depending on the direction of the charge flow[6,7] In both cases, the devices are based on the spin-filter concept with a permanent magnet. This effect was explained theoretically in several papers that included quantitative calculations[15,16,17,18]

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