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Finnish SPIN researchers at forefront of development: Spintronics can bring electronics down to size

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18.03.2005

Researchers working on the room temperature spintronics (SPIN) research project are the first in Europe to successfully produce GaMnN layers, which are ferromagnetic at room temperature. The layer properties were examined using electric, optic, x-ray and positron measurements. The Academy-funded SPIN project is comprised of four participating entities, i.e. the Helsinki University of Technology (HUT) Departments of Electron Physics, Optoelectronics and Physics laboratories and the VTT Technical Research Centre of Finland Microelectronics research institute.

Headed by Dr Markku Sopanen, the SPIN project focuses on the research of manganese-doped gallium arsenide and gallium nitride. Gallium nitride is the most promising material for use in spintronics components which are operated at room temperature. The project also produced the first GaMnAs tunneling diode component, whose electrical properties are closely dependent on magnetic fields. High-speed tunneling diodes are used in, for example, microwave technologies.

Previously, ferromagnetic III-V semiconductors that functioned at room temperature were a completely unknown entity. Advances made in recent years have increased the ranks of ferromagnetic semiconductors with such compounds as GaMnAs clusters, InMnAs and GaMnN, whose Curie temperature is considerably higher than room temperature. Ferromagnetic III-V semiconductors are among the most interesting new material sectors in electronics and optoelectronics. These materials have a wide range of possible applications, in which the spin of electrons is used in electronic components. Examples include magnetic storage devices, magnetic field sensors, magnetically-controlled devices, spin transistors, polarisation-controlled optoelectronics devices and even quantum computing.

Magnetic semiconductors allow single components to perform multiple functions

Current spintronics (or magnetoelectronics) applications are based on magnetic metals. However, magnetic metals can only be used in applications based on memory, reader heads or magnetic sensors. Magnetic semiconductors, on the other hand, can be used in developing applications for these and other areas. Their key advantage is that multiple functions can be integrated in a single component, which can function simultaneously as a memory and amplifier.

Moreover, the advanced manufacturing techniques of semiconductors also allow spintronics components to be integrated in existing applications. Many magnetic phenomena are also more pronounced in magnetic semiconductors than in magnetic metals.

In state-of-the-art electronics data processing is based solely on the electron charge, whereas in spintronics it is based on both the electron charge and spin. The spins of electrons in the ferromagnetic material are put into the same direction using an externally-generated magnetic field, and the spins will continue in the same direction even after the magnetic field has been removed. The function of spintronics components is based on the fact that spins running in the same or opposite directions will alter the optical, electrical and magnetic properties of the component.

TULE conducts long-term, high-calibre basic research on electronics

The SPIN project is part of the Academy of Finland-funded Future Electronics (TULE) Research Programme, which is comprised of 18 research projects. The Programme is divided into following subject areas: circuits and systems; materials, optics and optoelectronics; and nanoelectronics.

The goal of the Programme is to conduct long-term, high-calibre basic research on electronics, which supports research and development in the Finnish electronics industry and can be used to innovate new applications. The Programme also aims to enhance scientific expertise and research environments in sectors vital to the current and future development of the Finnish electronics industry as well as to establish a qualified workforce required by growth in the field.

Terhi Loukiainen | Quelle: alphagalileo
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