Fyzikální ústav Akademie věd ČR

Over the past two decades, the research of ferromagnetic semiconductors, with (Ga,Mn)As as a prime example, has led to a deeper understanding of relativistic spin-dependent phenomena in magnetic systems. It has also led to discoveries of new effects and demonstrations of unprecedented functionalities in experimental micro-electronic and opto-electronic devices. Researchers from the Institute of Physics of the Academy of Sciences in Prague, in collaboration with researchers from the Charles University in Prague and from the UK, have published a comprehensive review of this active field of condensed matter physics in the journal Reviews of Modern Physics (DOI: 10.1103/RevModPhys.86.855).

Ferromagnetic semiconductors represent a favourable class of materials integrating the charge-based and spin-based functionalities of micro-electronic and opto-electronic devices. Semiconductor silicon microprocessors are prime examples among the large variety of charge-based devices. They utilize the possibility offered by semiconductors to easily electrically manipulate and detect their electronic charge states representing the zeros and ones. Spin-based devices operate on an entirely distinct principle. In some materials, like iron, electron spins spontaneously align their direction, what subsequently generates magnetism of such material. The position of the north and south pole of the magnet can be used to represent the zeros and ones. This technology is behind memory applications such as computer hard disks. Ferromagnetic-semiconductors can simultaneously behave like silicon and iron which offers the unique possibility to investigate the charge and spin functionalities in one material.

Figure shows a transistor with a (Ga,Mn)As ferromagnetic-semiconductor gate electrode which allows to open and close the transistor channel, in the same device, using either charge or spin.

The leading position of the Czech team in the international research of ferromagnetic semiconductors, acknowledged by the invitation to prepare the comprehensive Reviews of Modern Physics article, is an outgrowth of the decade’s materials development and device nano-fabrication activities, magnetic, electrical, and optical experiments, and an extensive theoretical modeling.

For detail information contact Tomas Jungwirth from the Institute of Physics ASCR, v. v. i., Cukrovarnická 10, 162 53 Praha 6, e-mail: jungwfzu [dot] cz