First spintronic components use commercial Si

Spintronic components (generation of electronic components of the future simultaneously exploiting the electronic properties as well as electrical charges) are gradually approaching commercial products after researchers in the United States confirmed They first " injected " spin-polarized electrons into silicon.

Ian Appelbaum of the components team research team (Photo: Vatlyvietnam)

In this tiny device, electrons are transferred from a ferromagnetic alloy to a Si layer, and travel about 10 micrometers without losing their polarity. At the same time, the group can rotate the direction of spin when electrons move through the silicon and the final electronic refractive index and measure their polarization. This is one of the first spintronic components to use Silicon material - extending commercial production capabilities ( This result has just been published in Nature, 447 295 ).

Spintronics components are electronic circuits that can use both electrical charge and spin simultaneously to transmit, store and process information . In principle, these components can speed up the performance of traditional computers, as well as promise the ability to develop quantum computers. Silicon can be an excellent material for these components because electrons can move farther than in metal without losing polarity. In addition, Silicon is the number one choice for the electronics industry, so spintronics components that use Si will be very compatible with today's commercial chip manufacturing technologies.

Another problem is that it is always impossible to bring spin-polarized electrons into Si at the starting point. Spin-polarized electrons always exist in ferromagnetic materials (such as iron), where most spins of conduction electrons are always oriented in the direction of magnetization. If a ferromagnetic metal layer is applied to the Si layer, the electrons will be driven from the scratched iron in Si by placing a voltage. Unfortunately, electronics often lose spin polarization as they move through the transition zone between two layers of material due to impedance mismatch between metal and semiconductor.

This problem can be solved in a number of other semiconductor materials such as GaAs by allowing spin-polarized electrons to tunnel through the transitional layer, thus limiting the " impedance mismatch " effect. However, this requires a very thin and instantaneous transition layer between metal and semiconductor, and is difficult to achieve when creating ferromagnetic metal layers growing on Si.

Figure 1. Image of the structure of the layers of components and components observed from the outside
(According to Nature, 447 295).

And recently, Ian Appelbaum and Biqin Huang's group at Delaware University (USA) and Douwe Monsma (Cambridge NanoTech, Massachusetts, USA) have found a way to solve this problem by creating "electronics." hot " goes through the transition layer between metal and semiconductor. Instead of behaving like currents controlled by voltage (which will be affected by impedance) - these electrons act like bullets fired through transitional layers and not at all create impedance effect. As a result, these "ballistic electrons" will pass through the Si layer without losing polarity.

Figure 2. Some results of the study: curvature from late and transport
electronics in components (According to Nature, 447 295).

First, the researchers created hot electrons in a tunneling contact attached to a 5 nm CoFe alloy layer. The electrons will be injected into the ferromagnetic layer (to form spin-polarized molecules) and they will move to the second ferromagnetic layer (to measure spin polarization) after moving through the Si layer. When a magnetic field is applied to the component, the direction of the polarization spin can be rotated when the electron passes through the Si layer. The degree of precession can be changed by changing magnetic fields or changing the velocity of electrons by placing an electric field. By observing this precession, the researchers can confirm that the electron actually retains its spin polarization when stripping the Si layer.

Measurements were carried out at 85 K to minimize leakage currents in the components. While such low temperatures are almost unrealistic, Appelbaunm told Physics Web that the device has created a new perspective and extremely important results for materials science and research. about spin transport in Si, a practical result for spintronic devices that can reach the trade item.

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