Spintronics-Info: the spintronics experts

Researchers from the NREL and the University of Utah have demonstrated how electron transport with a particular spin state through a two-dimensional hybrid organic-inorganic perovskite can be manipulated by introducing special organic molecules in the multilayer structure.

One way to control spin-polarized currents is through "chiral-induced" spin selectivity where the transport of electrons depends upon the transporting materials’ chirality—a structural property of a system where its mirror image is not superimposable on itself. The scientists have demonstrated how to integrate a chiral organic sublattice into an inorganic framework, creating a chiral system that can transport electrons with the desired spin control. In such systems, the chiral perovskite films act as a spin filter.

Researchers from Spain's ICN2 institute have used numerical simulations to show that spin diffusion length in graphene is independent of grain size. The researchers base their calculations on CVD grown graphene. CVD methods produces high quality materials that are built from several single-crystal sheets separated from one another through grain boundaries.

The research have shown that the grain boundaries do not have any effect on the spin transport. The researchers considered two different mechanisms for spin relaxation - randomization of spins within the grains due to spin-orbit coupling, and scattering in a grain boundary. The main implication of this research is that single-domain graphene may not be a requirement for spintronics applications.

The International Institute of Physics in Brazil recently uploaded this interesting talk by Ahmet Avsar, from the EPFL, who discusses spintronics in 2D materials (such as graphene):

This talk was given as part of the IIP's 2D Materials: From Fundamentals to Spintronics workshop which took place in early October.

An international team of researchers from France and Sweden designed a new concept of an energy harvesting engine based on spintronics and quantum thermodynamics. The basic idea is to use electron spin to harvest thermal fluctuations at room temperature.

The researchers make use of the fact that paramagnetic centers, or atom-level magnets, fluctuate their spin orientation due to heat. In the so called spin-engine, the a spontaneous bias voltage V appears between the electrodes, and thus a spontaneous current flows once the electrical circuit is closed.

There are still many challenges to create such devices (the team made some initial experiments) - but the researchers say that this concept could create chips that continuously produce electrical power with a power density that is 3x greater than raw solar irradiation on Earth.

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 Japan's National Institute for Materials Science (NIMS) have managed to introduce a quantum well structure into a conventional magnetic tunnel junction (MTJ). The researchers say that the QW structure can enhance the tunneling magnetoresistance (TMR) ratio by spin-dependent resonant tunnel (SDRT) effect, with a value of 1.5 times comparing with no SDRT case, at room temperature.

The researchers tell us that the key point of the QW formation is the band mismatch between Cr and Fe for majority band, and the mismatch-free Fe/MgAl₂O₄ interface. The finding is not just useful for enhancement of TMR ratio, it also provides a benefit that the TMR ratio could be kept almost constant in a wide bias voltage range of from -1V to 0.5V.

Researchers from the University of Groningen developed a two-dimensional spin transistor, in which spin currents were generated by an electric current through graphene. The device also include a monolayer transition metal dichalcogenide (TMD) that is placed on the graphene to induce charge-to-spin conversion.

Graphene is an excellent spin transporter, but spin-orbit coupling is required to create or manipulate spins. The interaction is weak in the graphene carbon atoms, but now the researchers have shown that adding the TMD layer increases the spin-orbit coupling.