Researchers from the University of Delaware confirmed that electrons generate a magnetic field. In materials made from two layers of a heavy metal and a ferromagnetic material, the spin current diffuses into the ferromagnetic material. When this happens, a magnetic field is generated.

This magnetic field does not radiate beyond the ferromagnetic material (unlike regular magnetic fields). This is important in applications such as MRAM in which shielding the magnetic fields between memory cells is difficult. If devices use the new magnetic field it may be easier to create high density MRAM cells or other devices.

Theoretical research by A*STAR researchers in Singapore shows that spin-polarized current can simply be achieved by applying an oscillating voltage across the device. Spin-polarized is critical for Spintronics devices, but imperfections in a material can easily destroy the polarization.

The researchers looked at a two-dimensional electron gas (in which the electrons can move only in one plane). If you pass a spin-polarized current through this gas, a Rashba spin-orbit coupling effect makes the spin change (first upwards and then downwards) - which reduces the polarization to zero. Using a spin-current rectifier (like a spin polarization filter) one can control the strength of the Rashba coupling effect and so prolong the spin current's polarization life.

Researchers from the Japanese RIKEN institute have shown that spin information in some materials can travel much further than previously thought. The researchers managed to measure the spin diffusion in detail by using two magnetic contacts to inject the spin signal into a thin silver wire. This enhances the amount of spin polarization present in the wire. Using a third contact that picks the signals, they were manage to manage the polarization degree at several distances along the wire.

They say that spin current was detected at distances of over ten micrometers. The absolute magnitude of the spin signal decreases with travel distance, but the quality of the spin precession signal (coherence) is actually improved - due to the fact that the collective coherent precession of the spins has a beneficial effect on the overall spin polarization over time.

Researchers from Cambridge University developed a more efficient way to generate spin current, using the collective motion of spins called spin waves (the wave property of spins). There are a number of different interactions in spin waves and the researchers's idea was to use such spin wave interactions for generating efficient spin currents.

One of the spin wave interactions (called three-magnon splitting) generates spin current 10 times more efficiently than using pre-interacting spin-waves.

Researchers from the City University of Hong Kong managed to generate a spin current in Graphene, which could lead us to using Graphene as a spintronics device.

The scientists used spin splitting in monolayer graphene generated by ferromagnetic proximity effect and adiabatic (a process that is slow compared to the speed of the electrons in the device) quantum pumping. They can control the degree of polarization of the spin current by varying the Fermi energy (the level in the distribution of electron energies in a solid at which a quantum state is equally likely to be occupied or empty), which they say is very important for meeting various application requirements.

Researchers from the Hitachi Cambridge Laboratory in the University of Cambridge developed a new technology that enables the control (and detection) of spin current. The idea is to use laser light to sustain the spin signal during transit and to manipulate it by applying a voltage. The detection is done electrically.

The team admits that for high-volume information processing this will not really be practical, but this method proves the spin-transistor principle and it be lay the ground work for next-generation devices.

Researchers from the Institut Català de Nanotecnologia (ICN), in Barcelona have demonstrated a new device that induces electron spin motion without net electric current. They call this device a 'ratchet', in analogy to a ratchet wrench which provides uniform rotation from oscillatory motion. The Spin Ratchets achieve directed spin transport in one direction, in the presence of an oscillating signal. Most important, this signal could be an oscillatory current that results from environmental charge noise; thus future devices based on this concept could function by gathering energy from the environment.

The ratchet efficiency can be very high - reported results show electron polarizations of the order of 50%, but they could easily exceed 90% with device design improvements. The spin ratchet, which relies on a single electron transistor with a superconducting island and normal metal leads, is able to discriminate the electron spin, one electron at a time. The devices can also function in a “diode” regime that resolves spin with nearly 100% efficacy and, given that they work at the single-electron level, they could be utilized to address fundamental questions of quantum mechanics in the solid state or to help prepare the path for ultrapowerful quantum or spin computers.

Paul Haney and Mark Stiles from the NIST Center for Nanoscale Science and Technology (CNST) developed a new theory of current-induced torques that generalizes the relationship between spin transfer torques, total angular momentum current, and mechanical torques. This new theory is also applicable to more materials than previous theories.

The basic idea is that there are two types of current-induced torques: a mechanical torque acting on the lattice, and a spin transfer torque (STT) acting on the magnetization. STT is a known phenomenon that is the basic of several technologies such as STT-MRAM and nanoscale microwave oscillators.

A short video about the University of Tokyo's Ohtani Laboratory spintronics research, which is focused on spin-polarized current and pure spin current:

In magnetic memory devices, information is stored in magnetic elements and typically retrieved by applying a small, external magnetic field. More convenient, however, is the use of a spin-polarized current, in which moving electrons exert a torque on a magnetic element and can switch the direction of its magnetization.

Unfortunately, moving electrons can give rise to electrical noise, which reduces the efficiency of the magnetization control. Now, Yoshichika Otani from the RIKEN Advanced Science Institute in Wako and colleagues have overcome this problem by using a pure spin current*, that is, a diffusion of electron spins without charge motion.

By examining the electronic transport properties of their device, the researchers were able to demonstrate that when the current injected into the first junction is high enough, it creates a spin current high enough to reverse the magnetization at the second junction. Most importantly, the magnetization can be reversed back by applying the same amount of current in the opposite direction.

Via  AZONano