[mwLogo]

Computer simulations of spin-dependent electronic transport in semiconductor quantum wires

NCN grant 2011/03/B/ST3/00240

Results Team Publications Conferences

Introduction / Wprowadzenie

In the framework of the project, we have proposed a possible realization of the spin transistor and the spin separator based on the semiconductor nanowires, i.e., nanostructures with length on the order of few micrometers and diameter of several nanometers. We have developed a theoretical description of the spin transistor, a device for controlling the spin current, i.e., the flow of electrons with identical spins. Our findings are consistent with the results of experiments carried out for nanowires operating under voltage applied to the side electrode. We have also proposed the construction of the spin separator based on the Y-shaped nanostructure. The Y-shaped spin separator can operate in an external magnetic field and at the appropriate voltage applied to one of the output branches. If the unpolarized current is injected into the input branch of the Y-shaped nanostructure, then the spin-polarized currents with opposite spins flow out through the two output branches. This device, operating under optimal conditions, enables the full separation of spin currents without any loss of current. We have also studied the possibility of the manipulation of the electron spin states in core-shell nanowires, composed of concentric cylindrical regions made of different semiconductor materials. We have shown that the external magnetic field is not necessary to effectively control the spin of electrons, but instead it is sufficient to use the external electric field that generates the internal magnetic field acting on the spin of the electron via the relativistic spin-orbit interaction.

The results of the project allow us to understand the physical principles of the control of spin currents in semiconductor nanowires, provide a description of experimental data, and a design of novel spintronic devices. We expect that our results will help in the further development of spin electronics, which can provide the society with new useful devices.

○ ● ○ ● ○

W ramach projektu zaproponowaliśmy możliwe realizacje tranzystora spinowego i separatora spinów na bazie nanodrutów półprzewodnikowych, czyli nanostruktur o długości rzędu mikrometra i średnicy rzędu kilkunastu/kilkudziesięciu nanometrów. Opracowaliśmy opis teoretyczny tranzystora spinowego, przyrządu do sterowania prądem spinowym, czyli przepływem elektronów o jednakowych spinach. Otrzymane przez nas wyniki są zgodne z wynikami doświadczeń wykonanych dla nanodrutów kontrolowanych napięciem przyłożonym do bocznej elektrody. Zaproponowaliśmy konstrukcję separatora spinów w oparciu o nanostrukturę o kształcie Y. Separator spinów działałby w zewnętrznym polu magnetycznym po podłączeniu odpowiedniego napięcia bocznego do jednej z gałęzi wyjściowych. Jeżeli do gałęzi wejściowej nanostruktury Y wpływałby prąd niespolaryzowany, to przez obie gałęzie wyjściowe wypływałyby prądy spolaryzowane spinowo o przeciwnych spinach. Przyrząd taki, działający w optymalnych warunkach, umożliwiłby pełną separację prądów spinowych bez strat prądu. Zbadaliśmy również możliwość manipulacji spinem elektronu w nanodrucie o strukturze rdzeniowo-powłokowej, czyli strukturze złożonej ze współosiowych cylindrycznych warstw złożonych z różnych materiałów półprzewodnikowych. Pokazaliśmy, że do efektywnego sterowania spinami elektronów nie jest konieczne zewnętrzne pole magnetyczne, lecz wystarczy zastosowanie zewnętrznego pola elektrycznego, które wytwarza wewnętrzne pole magnetyczne działające na spinowy moment pędu elektronu wskutek relatywistycznego oddziaływania spin-orbita.

Wyniki projektu pozwalają na zrozumienie podstaw fizycznych sterowania prądem spinowym w nanodrutach półprzewodnikowych, podają opis danych doświadczalnych oraz propozycję nowych przyrządów spintronicznych. Spodziewamy się, że w oparciu o nasze wyniki nastąpi dalszy rozwój elektroniki spinowej, która może dostarczyć społeczeństwu nowych użytecznych urządzeń.

back to top ⤴

Results

  • Ref. [5]
    (top) Schematic of the nanowire with constriction: r0 is the radius of the nanowire outside the constriction, rc is the minimal radius of the nanowire in the region of constriction with length Lc, and L is the length of the nanowire, i.e. the distance between the source (S) and the drain (D). B is the magnetic field.
    (middle) Schematic of potential energy profile (blue curve) along the axis of the nanowire, energy levels En (n=0,1,2) (solid red lines) of the quasi-bound Stark states formed in the triangular quantum well, and the resonant-state energy (thick dashed line) in the transport window (gray rectangle).
    (bottom) Upper panel: transmission coefficient T as a function of electron energy E and drain-source voltage V for B=10 T; white dashed lines correspond to the energies of Stark resonances. Lower panel: white dots show the energy levels of the quasi-bound Stark states localized in the triangular quantum well between the source and the constriction barrier.
[fig]
  • Ref. [10]
    (top) Magnetoresistance as a function of the magnetic field B and the radius rc of the constriction.
    (bottom) Magnetoresistance as a function of radius rc of the constriction (dashed lines correspond to the results obtained when spin of the electrons is neglected).
[fig]
  • Ref. [3]
    (top) Schematic of the nanotube with two-dimensional electron gas. Fz - axial electric field, Fr - radial electric field.
    (bottom) Average value sz of z-spin component as a function of position along the nanowire axis.
[fig]
  • Ref. [4]
    (top) Dispersion relations E(k) for (a) source-gate, (b) gate, and (c) gate- drain regions of the nanowire. In panels (a)–(c), the vertical (red and blue) arrows show the spin orientations. (d) Schematic of the nanowire spin transistor. Electric field Fx of the gate acts in the central (gate) region of the nanowire with length Lg. L is the length of the nanowire.
    (bottom) Current I as a function of gate voltage Vg for the source-drain voltage Vds=0.6 V. Upper panel: the results of the calculations, lower panel: experimental data. The calculations have been carried out for the spin polarization P=0.4 [solid (red) curve] and P=1 [dashed (blue) curve].
[fig]
  • Ref. [6]
    (top) Schematic of the Y-shaped nanostructure with the Quantum Point Contact (QPC). The green regions show the QPC potential energy profile. The unpolarized charge current injected from contact 1 is separated in the QPC region into the two spin currents flowing out through contacts 2 and 3. Red (blue) arrows depict the spin-up (spin-down) currents. Magnetic field B is applied is the z direction.
    (bottom) Spin-up (red curves) and spin-down (blue curves) conductance as a function of the QPC confinement energy ℏω. P12 (P13) correspond to the electrons flowing from contact 1 to 3 (from 1 to 2). Changing the voltage applied to QPC alters ω, which in turn allows us to control the process of spin separation.
[fig]

back to top ⤴

Team

back to top ⤴

Publications

  1. M. Wołoszyn, J. Adamowski, P. Wójcik, B.J. Spisak, Periodicity of resonant tunneling current induced by the Stark resonances in semiconductor nanowire, J. Appl. Phys 114 (2013) 164301
  2. B.J. Spisak, M. Wołoszyn, P. Wójcik, Influence of Dephasing and Geometrical Parameters on Quantum Correction to DC Conductance of Cylindrical Nanowires, Acta Phys. Pol. A 124 (2013) 838
  3. P. Wójcik, J. Adamowski, M. Wołoszyn, B.J. Spisak, All-electrical manipulation of electron spin in a semiconductor nanotube, Physica E 59 (2014) 19
  4. P. Wójcik, J. Adamowski, B.J. Spisak, M. Wołoszyn, Spin transistor operation driven by the Rashba spin-orbit coupling in the gated nanowire, J. Appl. Phys. 115 (2014) 104310
  5. M. Wołoszyn, B.J. Spisak, J. Adamowski, P. Wójcik, Magnetoresistance anomalies resulting from Stark resonances in semiconductor nanowires with a constriction, J. Phys.: Condens. Matter 26 (2014) 325301
  6. P. Wójcik, J. Adamowski, M. Wołoszyn, B.J. Spisak, Spin splitting generated in a Y-shaped semiconductor nanostructure with a quantum point contact, J. Appl. Phys. 118 (2015) 014302
  7. P. Wójcik, J. Adamowski, M. Wołoszyn, B.J. Spisak, Resonant Landau–Zener transitions in a helical magnetic field, Semicond. Sci. Technol. 30 (2015) 065007
  8. M. Wołoszyn, P. Wójcik, B.J. Spisak, J. Adamowski, Spin conductance of nanowires with double coupled quantum dots, Acta Phys. Pol. A 129 (2016) A114
  9. T. Palutkiewicz, M.Wołoszyn, B.J.Spisak, J. Adamowski, P. Wójcik, Influence of geometrical parameters on the transport characteristics of gated core-multishell nanowires, Acta Phys. Pol. A 129 (2016) A111
  10. M. Wołoszyn, B.J. Spisak, P. Wójcik, J. Adamowski, Transition from positive to negative magnetoresistance induced by a constriction in semiconductor nanowire, Physica E 83 (2016) 127
  11. T. Palutkiewicz, M. Wołoszyn, B.J. Spisak, Junctionless transistor operation regime of the core-shell nanowire with electrostatic all-around gate, Semicond. Sci. Technol. (submitted)

back to top ⤴

Conferences

  1. 42nd Jaszowiec International School and Conference on the Physics of Semiconductors, Wisła 22-27.06.2013, B.J.Spisak M.Wołoszyn P.Wójcik, Influence of dephasing time and geometrical parameters on the quantum corrections to the conductivity of cylindrical nanowire
  2. 20th International Conference on Electronic Properties of Two-Dimensional Systems (EP2DS-20) and 16th International Conference on Modulated Semiconductor Structures (MSS-16), Wrocław 1-5.07.2013, P.Wójcik J.Adamowski B.J.Spisak M.Wołoszyn, Spin current polarization at room temperature in a nanowire resonant tunneling diode
  3. 5th International Conference on One-dimensional Nanomaterials, Annecy 23-26.09.2013, B.J.Spisak P.Wójcik M.Wołoszyn J.Adamowski, Computer simulations of spin transistor operation in InAs nanowire
  4. 5th International Conference on One-dimensional Nanomaterials, Annecy 23-26.09.2013, P.Wójcik J.Adamowski B.J.Spisak M.Wołoszyn, Modification of electron spin induced by the Rashba spin-orbit interaction in a semiconductor nanotube
  5. Energy-Materials-Nanotechnology Fall Meeting, Orlando 7-10.12.2013, J.Adamowski P.Wójcik B.J.Spisak M.Wołoszyn, Spin-polarized electron current modification in gated semiconductor nanowires
  6. 43rd Jaszowiec International School and Conference on the Physics of Semiconductors, Wisła 7-12.06.2014, M.Wołoszyn B.J.Spisak P.Wójcik J.Adamowski, Effect of a double constriction on the magnetotransport properties of semiconductor nanowires
  7. The European Conference Physics of Magnetism 2014 (PM'14), Poznań 23-27.06.2014, M.Wołoszyn B.J.Spisak P.Wójcik J.Adamowski, Large magnetoresistance effect in cylindrical semiconductor nanowires with constriction
  8. The European Conference Physics of Magnetism 2014 (PM'14), Poznań 23-27.06.2014, B.J.Spisak M.Wołoszyn J.Adamowski P.Wójcik, Spin-dependent magnetotransport in semiconductor nanowires
  9. From Spins to Cooper Pairs: New Physics of the Spins (StoCP-2014) Topical Conference: 650th Jubilee of the Jagiellonian University, Zakopane 22-26.09.2014, P.Wójcik J.Adamowski B.J.Spisak M.Wołoszyn, Spin transistor action driven by the helical magnetic field
  10. From Spins to Cooper Pairs: New Physics of the Spins, Zakopane 22-26.09.2014, J.Adamowski P.Wójcik M.Wołoszyn B.J.Spisak, Physics of nanowire spintronic devices
  11. Nanoscience and Nanotechnology International Conference nanoPT, Porto 11-13.02.2015, P.Wójcik J.Adamowski M.Wołoszyn B.J.Spisak, Generating and Detecting the Spin Current in Y-shaped Semiconductor Nanowire with Quantum Point Contact
  12. Theory, Modelling and Computational Methods for Semiconductors, Granada 28-30.01.2015, M.Wołoszyn B.J.Spisak P.Wójcik J.Adamowski, Spin-dependent magnetotransport properties of double-gate semiconductor nanowires
  13. Theory, Modelling and Computational Methods for Semiconductors, Granada 28-30.01.2015, B.J.Spisak M.Wołoszyn P.Wójcik J.Adamowski, Spin-dependent magnetotransport through quantum point contact in semiconductor nanowires
  14. 44th Jaszowiec International School and Conference on the Physics of Semiconductors, Wisła 20-25.06.2015, T.Palutkiewicz M.Wołoszyn P.Wójcik J.Adamowski B.J.Spisak, Influence of geometrical parameters on the transport characteristics of gated core-multishell nanowires
  15. 44th Jaszowiec International School and Conference on the Physics of Semiconductors, Wisła 20-25.06.2015, M.Wołoszyn J.Adamowski P.Wójcik B.J. Spisak, Spin conductance of nanowires with double coupled quantum dots
  16. SPINTECH VIII International School and Conference, Basel 10-13.08.2015, P.Wójcik J.Adamowski M.Wołoszyn B.J.Spisak, Effect of nonadiabaticity on spin transitions in helical magnetic field

back to top ⤴

About this page...

Valid HTML 4.01 Strict