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Title: Nonequilibrium spin transport through a diluted magnetic semiconductor quantum dot system with noncollinear magnetization

Abstract

The spin-dependent transport through a diluted magnetic semiconductor quantum dot (QD) which is coupled via magnetic tunnel junctions to two ferromagnetic leads is studied theoretically. A noncollinear system is considered, where the QD is magnetized at an arbitrary angle with respect to the leads' magnetization. The tunneling current is calculated in the coherent regime via the Keldysh nonequilibrium Green's function (NEGF) formalism, incorporating the electron-electron interaction in the QD. We provide the first analytical solution for the Green's function of the noncollinear DMS quantum dot system, solved via the equation of motion method under Hartree-Fock approximation. The transport characteristics (charge and spin currents, and tunnel magnetoresistance (TMR)) are evaluated for different voltage regimes. The interplay between spin-dependent tunneling and single-charge effects results in three distinct voltage regimes in the spin and charge current characteristics. The voltage range in which the QD is singly occupied corresponds to the maximum spin current and greatest sensitivity of the spin current to the QD magnetization orientation. The QD device also shows transport features suitable for sensor applications, i.e., a large charge current coupled with a high TMR ratio. - Highlights: Black-Right-Pointing-Pointer The spin polarized transport through a diluted magnetic quantum dot is studied. Black-Right-Pointing-Pointermore » The model is based on the Green's function and the equation of motion method. Black-Right-Pointing-Pointer The charge and spin currents and tunnel magnetoresistance (TMR) are investigated. Black-Right-Pointing-Pointer The system is suitable for current-induced spin-transfer torque application. Black-Right-Pointing-Pointer A large tunneling current and a high TMR are possible for sensor application.« less

Authors:
 [1];  [2]
  1. Computational Nanoelectronics and Nano-device Laboratory, Electrical and Computer Engineering Department, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore)
  2. Data Storage Institute, A-STAR (Agency of Science, Technology and Research), DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore)
Publication Date:
OSTI Identifier:
22157080
Resource Type:
Journal Article
Journal Name:
Annals of Physics (New York)
Additional Journal Information:
Journal Volume: 330; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0003-4916
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; ANALYTICAL SOLUTION; APPROXIMATIONS; COUPLING; EQUATIONS OF MOTION; GREEN FUNCTION; MAGNETIC SEMICONDUCTORS; MAGNETIZATION; MAGNETORESISTANCE; QUANTUM DOTS; SENSORS; SPIN; SPIN ORIENTATION; TUNNEL EFFECT

Citation Formats

Ma, Minjie, Jalil, Mansoor Bin Abdul, E-mail: elembaj@nus.edu.sg, Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 1 Engineering Drive 3, Singapore 117576, and Tan, Seng Gee. Nonequilibrium spin transport through a diluted magnetic semiconductor quantum dot system with noncollinear magnetization. United States: N. p., 2013. Web. doi:10.1016/J.AOP.2012.11.016.
Ma, Minjie, Jalil, Mansoor Bin Abdul, E-mail: elembaj@nus.edu.sg, Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 1 Engineering Drive 3, Singapore 117576, & Tan, Seng Gee. Nonequilibrium spin transport through a diluted magnetic semiconductor quantum dot system with noncollinear magnetization. United States. https://doi.org/10.1016/J.AOP.2012.11.016
Ma, Minjie, Jalil, Mansoor Bin Abdul, E-mail: elembaj@nus.edu.sg, Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 1 Engineering Drive 3, Singapore 117576, and Tan, Seng Gee. Fri . "Nonequilibrium spin transport through a diluted magnetic semiconductor quantum dot system with noncollinear magnetization". United States. https://doi.org/10.1016/J.AOP.2012.11.016.
@article{osti_22157080,
title = {Nonequilibrium spin transport through a diluted magnetic semiconductor quantum dot system with noncollinear magnetization},
author = {Ma, Minjie and Jalil, Mansoor Bin Abdul, E-mail: elembaj@nus.edu.sg and Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 1 Engineering Drive 3, Singapore 117576 and Tan, Seng Gee},
abstractNote = {The spin-dependent transport through a diluted magnetic semiconductor quantum dot (QD) which is coupled via magnetic tunnel junctions to two ferromagnetic leads is studied theoretically. A noncollinear system is considered, where the QD is magnetized at an arbitrary angle with respect to the leads' magnetization. The tunneling current is calculated in the coherent regime via the Keldysh nonequilibrium Green's function (NEGF) formalism, incorporating the electron-electron interaction in the QD. We provide the first analytical solution for the Green's function of the noncollinear DMS quantum dot system, solved via the equation of motion method under Hartree-Fock approximation. The transport characteristics (charge and spin currents, and tunnel magnetoresistance (TMR)) are evaluated for different voltage regimes. The interplay between spin-dependent tunneling and single-charge effects results in three distinct voltage regimes in the spin and charge current characteristics. The voltage range in which the QD is singly occupied corresponds to the maximum spin current and greatest sensitivity of the spin current to the QD magnetization orientation. The QD device also shows transport features suitable for sensor applications, i.e., a large charge current coupled with a high TMR ratio. - Highlights: Black-Right-Pointing-Pointer The spin polarized transport through a diluted magnetic quantum dot is studied. Black-Right-Pointing-Pointer The model is based on the Green's function and the equation of motion method. Black-Right-Pointing-Pointer The charge and spin currents and tunnel magnetoresistance (TMR) are investigated. Black-Right-Pointing-Pointer The system is suitable for current-induced spin-transfer torque application. Black-Right-Pointing-Pointer A large tunneling current and a high TMR are possible for sensor application.},
doi = {10.1016/J.AOP.2012.11.016},
url = {https://www.osti.gov/biblio/22157080}, journal = {Annals of Physics (New York)},
issn = {0003-4916},
number = ,
volume = 330,
place = {United States},
year = {2013},
month = {3}
}