Spin Valve

An international team of researchers has succeeded for the first time to elucidate how ultrafast spin-polarized current pulses can be characterized by measuring the ultrafast demagnetization in a magnetic layer system within the first hundreds of femtoseconds.

The scheme shows (from left to right): Hot electrons generated by a laser in platinum (light blue), the copper (yellow) is used to block the laser pulse so that only the hot electrons propagate and transport a spin current through the magnetic spin valve structure of cobalt platinum (blue-brown) and iron gadolinium (green). Image credit: HZB

The findings could be useful for the development of spintronic devices that enable faster and more energy-efficient information processing and storage. The collaboration involved teams from the University of Strasbourg, HZB, Uppsala University and several other universities.

A team of researchers from CIC nanoGUNE, IKERBASQUE, IMEC and CNRS have reported a spintronic device that leverages proximity effects alone, specifically a 2D graphene-based spin valve. The functioning of this valve relies only on the proximity to the van der Waals magnet Cr₂Ge₂Te₆. Spin precession measurements showed that the graphene acquires both spin–orbit coupling and magnetic exchange coupling when interfaced with the Cr₂Ge₂Te₆. This leads to spin generation by both electrical spin injection and the spin Hall effect, while retaining spin transport. The simultaneous presence of spin–orbit coupling and magnetic exchange coupling also leads to a sizeable anomalous Hall effect.

The primary objective of this recent study was to tackle a long-standing research challenge, namely that of realizing the first-ever seamless 2D spintronic device. The spin valve they developed could enable the manipulation and transport of spin entirely in the 2D plane.

Researchers from the University of Groningen created curved spin transport channels. The researchers discovered that this new geometry makes it possible to independently tune charge and spin currents.

Most spintronics devices to date were made from flat surfaces, and this research focused on spin currents behaviors in curved channels. The scientists say that the new research enables the efficient integration of spin injectors and detectors or spin transistors into modern 3D circuitry.

Researchers from the University of Utah developed two spintronics devices based on perovskite materials. The researchers use these new devices to demonstrate the high potential of perovksites for spintronics systems. This is a followup to the exciting results announced in 2017 by the same group that showed advantages of perovskites for spintronics.

The researchers use an organic-inorganic hybrid perovskite material that has a heavy lead atom that features strong spin-orbit coupling and a long injected spin lifetime.The first device is a spintronic LED which works with a magnetic electrode instead of an electron-hole electrode. The perovskite LED lights up with circularly polarized electroluminescence.

Researchers from Germany's Helmholtz-Zentrum Dresden-Rossendorf (HZDR) developed and tested a new technique to fabricate spin valves using ion beams. The researchers managed to structure an iron aluminium alloy in such a way as to subdivide the material into individually magnetizable regions at the nanometer scale - and function as a spin valve.

This is a different approach to standard spin valves, made from successive non-magnetic and ferromagnetic layers. The new spin valves has a lateral spin valve geometry, where the different magnetic regions are organized one next to the other as opposed to in layers one on top of the other. This enables the spin valves to work in parallel on large surfaces, and also means that that the production costs are low.

Researchers from the Helmholtz Center in Berlin developed a new magnetic valve that can be used for data storage or information processing. The new structure allows an indefinite number of re-write cycles.

The researchers created a defined anisotropy with two thin, stacked ferromagnetic layers: they wanted to create a structure in which a magnetic characteristic within the material changes in a well defined way. They added a third non-magnetic layer (made of Tantalum) between the two layers, which made the whole structure behave like a spin valve.

We've got some more information about the SPIN project we reported on yesterday:

The SPIN project aims at demonstrating the potential impact and competitiveness of a new generation of components incorporating in a single chip nanoscience spintronics elements and CMOS technology. The basic proof of concept has already been brought that integration of these different technologies can provide highly innovative components, with the potential to become generic parts for many different products covering health, energy monitoring, domotics, automotive, aeronautics, and electronics. This project is thus focused on the development of a comprehensive set of three key demonstrators carefully chosen to provide a wide validation of such functionalities. These three objectives share very similar underlying technologies, so there is a large part of common work in their development, and our consortium gathers comprehensive expertise at the leading edge of the area.
Each demonstrator will be delivered with a report on the risk of industrialization, the life time targeted and the security and environmental impact, which will serve as basis for future industrialization.

Objective 1 : Magnetic FPGAs

The objective will be to design a magnetic FPGA which will incorporate finely distributed Magnetic Tunnel Junctions (MTJs) for non volatile storage and configuration purposes above of a CMOS core circuit. In complement of existing high density FPGAs, it will provide better versatility with intrinsic reconfigurability, instant on/off and energy saving. Such FPGAs can be used as general purpose standalone products. In the SPIN project, the FPGA will be targeted to provide intelligent processing of the magnetometers and sensors developed in objectives 2 and 3.