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Semiconductors Ferromagnetism at Room Temperature

#3818


Intrinsic Room Temperature Ferromagnetism, Magnetic Moments and Magneto-Optical Effects in Elemental and Oxide Semiconductors

Tech Area / Field

  • MAT-OTH/Other/Materials
  • PHY-SSP/Solid State Physics/Physics

Status
3 Approved without Funding

Registration date
03.09.2007

Leading Institute
State Research and Design Institute of Rare-Metal Industry, Russia, Moscow

Supporting institutes

  • Kurchatov Research Center, Russia, Moscow\nMoscow State University / Department of Physics, Russia, Moscow

Collaborators

  • Toyohashi University of Technology, Japan, Toyohashi\nUniversita degli Studi di L`Aquila / Dipartimento di Fisica, Italy, L`Aquila

Project summary

There is currently a lot of interest in the science and potential technological applications of spin-transport electronics (spintronics), in which the spin of charge carriers is exploited to provide new functionality for microelectronics and magneto-optics devices. In order to become a practical technology, semiconductor spintronics requires the discovery and use of ferromagnetic semiconductors that exhibit spin polarization in the majority carrier band at and above room temperature. Intrinsic remanent magnetization would allow spin-polarized currents to propagate in such materials without the need for a continuous magnetic field. One of the goals of this project just is the search of creation ways of single-phase elementary and oxide semiconductors with room-temperature intrinsic ferromagnetism and high magnetic moments suitable for use in devices of new electronic technique area – spin electronic, first of all for creation of semiconductor spin injectors.

Besides, the priority direction in many physical and technical areas is also development of the methods and the materials for optical information transfer and processing. The ferromagnetic semiconductors, the development of which is the object of this work, will ensure further increase of the operating speed of computers and of the density of magnetic storage. Thus, the second aim of the project is the study of possibility of such materials using for creation of the elements of another arising technique area – semiconductor magneto-photonics.

Hitherto developed in several laboratories ferromagnetic semiconductors, mainly on the base of ÀIIIBV compounds, keep the ferromagnetic ordering only at relatively low temperatures. These materials have not also got at room temperature the sufficient level of other necessary parameters, the major between them is the polarization degree of electron spins in the material. Besides that, the majority of studied ferromagnetic semiconductors (both compound and oxide) contain magnetic clusters inside, which makes them inappropriate for device applications. Reliable methods of fabrication the intrinsic single-phase ferromagnetic semiconductors have not been developed so far. Moreover, the systematic studies of distinct contribution into impurity-related magnetic moment of orbital and spin magnetic moments were not carried out. At the same time, modern concepts assume that an orbital magnetic moment of impurity atoms does not contribute into effective spin polarization in semiconductors, and thus, the study of the factors which determine total impurity-related magnetic moment in noted materials seems necessary.

In frames of the project it is supposed to synthesize film materials on the base of metal IV-group oxides and silicon, both doped with transition metal impurities, as well as to implant silicon wafers by the same impurities, to get intrinsic ferromagnetic semiconductors at above room temperature and to investigate their properties comprehensively. On the base of noted study we plan to develop fabrication methods of single-phase intrinsic ferromagnetic semiconductors without clusters. In addition, it is expected to found the fabrication conditions leading to the maximal spin magnetic moment and to determine total magnetic moment values in different ferromagnetic semiconductors studied. Pilot samples of the materials will be prepared with the parameters necessary for their use as effective spin injectors in spin electronics devices. The commercial samples of ferromagnetic semiconductor materials appropriate for spin electronics have not been hitherto available.

Materials investigation will be carried out by precise XRD analysis, local energy dispersive X-ray method, optical, Auger- and photoelectron spectroscopy, deep level transient spectroscopy, various EXAFS -techniques, atomic force- and tunnel microscopy, vibrating sample magnetometry and magnetooptics, the last in Kerr- and Faraday- effect modifications techniques. The basic manufacturing method will be RF magnetron sputtering. Films will be deposited on the lattice parameter compatible substrates. Besides, the samples will be made by ion implantation and laser ablation methods. The last technique utilizes two crossed molecular beams ensuring the deposition of only the high-dispersion fraction of a pulverized material and therefore high crystalline perfection of the material deposited.

It should be noted, that all above mentioned scientific and technological equipment is the property of the organizations participating in the project. Most of them is not new, but still in good conditions.


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