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Spin-polarized transport in ferromagnetic semiconductors

#G-1335


Comprehensive analysis of the spin transport in discrete alloys „semiconductor – ferromagnet“ with controlled disorder

Tech Area / Field

  • MAT-SYN/Materials Synthesis and Processing/Materials
  • INF-SIG/Sensors and Signal Processing/Information and Communications
  • PHY-SSP/Solid State Physics/Physics

Status
8 Project completed

Registration date
03.08.2005

Completion date
22.06.2010

Senior Project Manager
Lapidus O V

Leading Institute
Georgian Technical University, Georgia, Tbilisi

Supporting institutes

  • State University of Nizhny Novgorod / Research Physical and Technical Institute, Russia, N. Novgorod reg., N. Novgorod\nKurchatov Research Center, Russia, Moscow

Collaborators

  • Silicon Storage Technology, Inc., USA, CA, Sunnyvale

Project summary

Spintronics, based on usage of magnetic semiconductors, represents new and roughly educing area of science and engineering of the XXI century. The reason to that is the perspective of development and creation of principally new materials and devices for information technologies operating as charge, and spin degree of freedom of carriers, free from limitations inherent for metal spintronic devices.

The essential effort of the scientists are concentrated on studying of the spin-polarized transport in _ultiplayer structures which are including alternating layers of ferromagnetic metals and non-magnetic semiconductors. The central task of such researches is the creation of systems with effective spin injection into a non-magnetic semiconductor. The relevant role in solution of this problem is shunted to search and investigations of new ferromagnetic materials, which are capable to be reliable and effective spin injectors. Among such objects the magnetic discrete alloys are very promising. They are _ultiplayer systems composed of submonolayers of a ferromagnetic material in the matrix of a non-magnetic semiconductor, for example, Mn/GaAs or Mn/GaSb. It is well known, that these alloys have high Curie temperatures and sufficiently high spin polarization. The circumstance is not less important that it is possible to control and to manage of the “ferromagnetic metal – semiconductor” boundary surface immediately during the synthesis of these materials.

It is proposed to realize within the framework of the project a new approach for studying of discrete alloys. It is based as on the possibility of a controlled change of the degree of the magnetic disordering, so on the complex investigations of structural, chemical and magnetotrasport properties of these materials. The technological part of the project reputes development and creation of a new technology for obtaining of the Mn/GaAs and Mn/GaSb discrete alloys by a method of the MOS hydride epitaxy and laser epitaxy with usage of pulsed annealing of epitaxial layers. These technologies are rather simple and, at the same time, allow to perform the doping of layers under the oversaturated condition. The research and development part of the project includes magnetotrasport measurements, extraordinary and planar Hall Effect measurements, study of the magnetoresistance relaxation and mesoscopic fluctuations of the Hall voltage and theoretical interpretation of the obtained experimental outcomes.

Technological part of the project will be implemented mainly by scientists and engineers from the PTI NNGU and the GTU. The GTU will supply the necessary for the project purposes amount of Mn with the semiconducting purity. The discrete alloys syntes on the basis of a amorphous silicon hydride (α-Si:H) in combination with ferromagnetic 3-d metals (Fe and Co) is planned to carry out in the RRC “Kurchatov institute”. The main part of investigations of physical properties of all materials within the framework of the project is proposed to be conducted there also.

The offered comprehensive approach which includes technological, and broad-band fundamental researches as well, will allow achieving the purposes of the project in rather brief periods: 36 months. Thus, the scientists and engineers of the Russian research Center “Kurchatov institute” and the Georgian technical university, connected with the development of weapon production, will work in a close contact with the civil scientists and, in outcome, and will be redirected on solutions of problems having extremely peaceful scientific and practical value.

The project contributors have considerable experience of synthesis of _ultiplayer structures and low-dimensional materials, experimental research of their physical properties and theoretical description of transport properties of semiconductors. More than 40 articles in leading foreign and domestic physical magazines are published by results of these researches; the corresponding reports were regularly represented on international and Russian conferences.


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