Spin-Dependent Processes in Semiconductor Nanostructures


General Information

  1. Silicon nanoelectronics, optoelectronics and spintronics

    1. Spin-dependent transport in silicon gate-controlled rings
    2. Fractional forms of the 0.7 (2e2/h) feature in the quantum conductance staircase
    3. Quantum Conductance Metrology

  2. Quantum-Dimensional Superconductor-Semiconductor-Superconductor (SSS)
    Sandwich-Structures

    1. Interplay between the supercurrect quantization and quantum-dimensional quantization
    2. Multiple Andreev reflection
    3. Spin interference processes under magnetic resonance of single point
      defects embedded in quantum wells, wires and rings
    4. Quantum Interferometry on Josephson SSS sandwich-structures

Team


The silicon chemical vapour deposition (CVD) technology and techniques are the main basis of the technological group of this team (Prof. Dr. N.T. Bagraev, Dr. L.E. Klyachkin, Dr. A.M. Malyarenko) which allows the preparation of different kinds of silicon nanostructures such as ultra-narrow quantum wells, split-gated quantum wires, dots, one-dimensional rings and superconductor-silicon quantum well-superconductor sandwich-structures. The group is equipped with the spectrometer for the precise current-voltage measurements and the infrared spectroscopy equipment for the studies of the optical properties of semiconductor low-dimensional structures. The group has successful experience in the studies of the spin-dependent carrier transport and of the nuclear magnetic resonance (NMR) as well as electrically/optically induced nuclear polarization and electrically/optically detected ESR and NMR in both bulk and low-dimensional semiconductor structures.

The experimental group of the team (Prof. Dr. N.T.Bagraev, Prof. Dr. V.V.Romanov, Dr. L.E. Klyachkin, Dr. A.M. Malyarenko, PhD students: E.S. Brilinskaya, E.Yu. Danilovskiy, O.N. Guimbitskaya, A.A. Kudryavtsev, R.V. Kuzmin and Graduate students D.S. Gets, V.A. Rusakov) has a large experience in the measurements of the temperature and magnetic field dependencies of the quantum conductance and in the studies of the Coulomb blockade phenomena in semiconductor nanostructures. For last few years, the preparation and the investigation of the silicon quantum wells on the Si(100) surface were the main direction of activity. First results of experiments on the quantum conductance of holes, the single-hole memory operations at room-temperature as well as the spin-dependent transport in silicon quantum wells and rings that are confined by the high temperature superconductor barriers have been obtained. The experimental group is equipped with one of the best spectrometer for the measurements of temperature and magnetic field dependencies of the static magnetic susceptibility of semiconductor and superconductor low-dimensional structures. The group has a successful experience in the investigation of effects of the spin-orbit interaction, spin-dependent transport, and diamagnetic properties of two-dimensional electron/hole gases at silicon monocrystalline surface and in silicon quantum wells. The research of the group is particularly focused on the "0.7 feature" at the first plateau of the quantum conductance staircase as well as the spin interference phenomena and the asymmetric conductance resonances observed in the Datta and Das spin transistors and gate-controlled Aharonov-Bohm rings.

Overview of Research Activities

TASK 1:
Theoretical studies of the mechanisms of the AAS oscillations revealed by the spin interference due to the Rashba SOI in the gate-controlled AB rings are underway to define the relative contribution from the change of concentration and the spontaneous spin polarization of the carriers.

Milestone a:
The AAS oscillations in a double-slit one-dimensional ring.

TASK 2:
Theoretical studies of the three-terminal spin-interference device have to be carried out to develop the models of the effect of the QPC inserted on the spin-dependent transport, which will be a basis for the experimental realization of the spin splitter and the phase inverter.

Milestone b:
The spin splitter and the phase inverter based on the three-terminal spin-interference device.

TASK 3:
Preparation of high mobility self-assembled silicon quantum wells of the p-type on the n-type Si (100) wafers.

Milestone c:
The Rashba SOI in ultra-shallow silicon p+-n junctions.

TASK 4:
Theoretical and experimental studies of the oscillations of the magnetoresistance in weak magnetic fields have to be carried out to account for the high mobility of holes in self-assembled silicon quantum wells.

Milestone d:
THz and GHz Generation from self-assembled silicon nanostructures.

TASK 5:
Despite the experimental analysis of the evolution of the 0.7(2e2/h) feature from the 2e2/h to 3/2(2e2/h) values that seems to be related to the spontaneous spin polarization in the one-dimensional channel prepared inside the p-type silicon quantum well using the split-gate technique, further theoretical and experimental studies are necessary to define the relative contribution of the spontaneous spin polarization and the Rashba SOI in the spin-dependent transport in both one- and two-dimensional silicon nanostructures.

Milestone e:
The interplay of the spontaneous spin polarization and the Rashba SOI in the formation of the 0.7(2e2/h) feature.

TASK 6:
Theoretical and experimental studies of the three-terminal spin-interference device that represents the Si-based double-slit interferometer with the QPC inserted in the one of its arms is necessary to be carried out to define the relative contribution of the Rashba SOI, the spontaneous spin polarization and hyperfine interaction between single spin-polarized holes and the 29Si nuclei in both the phase and the amplitude of the AAS and AB conductance oscillations.

Milestone f:
Hyperfine interaction between single spin-polarized holes and the 29Si nuclei in one-dimensional rings



Contacts: Bagraev N.T.