A chiral-based magnetic memory device without a permanent magnet

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.

Robust Manipulation of Magnetism in Dilute Magnetic Semiconductor (Ga,Mn)As by Organic Molecules

“…Molecular spintronics, the study of electronic spin transport through molecular media and barriers as well as molecule/ solid-state interfaces, [ 10,11 ] has seen signifi cant progress, as exemplifi ed by the realization of organic spin-valves [ 12 ] and magnetic tunnel junctions, [ 13,14 ] spin fi ltering through chiral molecules, [ 15 ] and molecular spin memory devices. [ 16,17 ] The ferromagnetic-organic interface, as an essential component of molecular spintronic devices, has been the focus of many recent studies [ 18,19 ] due to the prospects of producing novel electrical and magnetic functionalities. So far, studies of molecular modifi cation of magnetism have mostly focused on metals where the effects are limited to the surface because of the large carrier densities and short screening lengths: [ 17,20 ] Both theoretical calculations [ 19,21 ] and experiments [ 15,16,19 ] have revealed possible presence of large spin polarization and spin-fi ltering effect at the interface of nonmagnetic organic molecules and …”

“…[ 16,17 ] The ferromagnetic-organic interface, as an essential component of molecular spintronic devices, has been the focus of many recent studies [ 18,19 ] due to the prospects of producing novel electrical and magnetic functionalities. So far, studies of molecular modifi cation of magnetism have mostly focused on metals where the effects are limited to the surface because of the large carrier densities and short screening lengths: [ 17,20 ] Both theoretical calculations [ 19,21 ] and experiments [ 15,16,19 ] have revealed possible presence of large spin polarization and spin-fi ltering effect at the interface of nonmagnetic organic molecules and …”

Control of Magnetism in Dilute Magnetic Semiconductor (Ga,Mn)As Films by Surface Decoration of Molecules

“…For instance, the ferromagnet-molecule interface has been the focus of many recent studies [43,44], due to their novel electrical and magnetic functionalities. Spinfiltering effect and large spin polarization at the interface of ferromagnetic metals and nonmagnetic organic molecules have been revealed both by theoretical calculations [44,45] and experiments [44,46,47]. Interfacial magnetization in the organic molecules may also be induced [48] and the surface magnetic anisotropy of the ferromagnetic metal be modified [49].…”

Spin-Dependent Effects in Helical Molecular Systems with Rashba-Like Spin-Orbit Interaction

“…Meanwhile, rst devices based on this high spin selectivity have been demonstrated: a chiralbased magnetic-based silicon-compatible memory device without a permanent magnet [9]. Spin-selective charge transfer through a self-assembled monolayer (SAM) of polyalanine was hereby used to magnetize a Ni layer with a magnetization that corresponds to applying an external magnetic eld of the order of 0.4 T to the Ni layer [9].…”