170 research outputs found
Macroscopic quantum effects of electromagnetic induction in silicon nanostructures
At room temperature, a macroscopic quantum galvanomagnetic effect of Faraday
electromagnetic induction was demonstrated under conditions of the capture of
single magnetic flux quanta in the edge channels, confined by chains of
negative-U centers, in a silicon nanostructure heavily doped with boron,
prepared in Hall geometry on an n-type Si (100) substrate. It is shown that
this effect leads to the appearance of an induction current when only a
constant magnetic field is applied in the absence of an externally applied
voltage or a stabilized current.Comment: 14 pages, 5 figure
Fractional quantum conductance staircase of edge hole channels in silicon quantum wells
We present the findings for the fractional quantum conductance of holes that
is caused by the edge channels in the silicon nanosandwich prepared within
frameworks of the Hall geometry. This nanosandwich represents the ultra-narrow
p-type silicon quantum well (Si-QW), 2 nm, confined by the {\delta}-barriers
heavily doped with boron on the n-type Si (100) surface. The edge channels in
the Si-QW plane are revealed by measuring the longitudinal quantum conductance
staircase, Gxx, as a function of the voltage applied to the Hall contacts, Vxy,
to a maximum of 4e2/h. In addition to the standard plateau, 2e2/h, the
variations of the Vxy voltage appear to exhibit the fractional form of the
quantum conductance staircase with the plateaus and steps that bring into
correlation respectively with the odd and even fractional values.Comment: 7 pages and 4 figure
Spin-dependent transport in p+-CdBxF2-x - n-CdF2 planar structures
The CV measurements and tunneling spectroscopy are used to study the
ballistic transport of the spin-polarized holes by varying the value of the
Rashba spin-orbit interaction (SOI) in the p-type quantum well prepared on the
surface of the n-CdF2 bulk crystal. The findings of the hole conductance
oscillations in the plane of the p-type quantum well that are due to the
variations of the Rashba SOI are shown to be evidence of the spin transistor
effect, with the amplitude of the oscillations close to e2/h.Comment: 5 pages, 6 figure
Spin interference in silicon three-terminal one-dimensional rings
We present the first findings of the spin transistor effect in the Rashba
gate-controlled ring embedded in the p-type self-assembled silicon quantum well
that is prepared on the n-type Si (100) surface. The coherence and phase
sensitivity of the spin-dependent transport of holes are studied by varying the
value of the external magnetic field and the bias voltage that are applied
perpendicularly to the plane of the double-slit ring. Firstly, the amplitude
and phase sensitivity of the 0.7(2e^2/h) feature of the hole quantum
conductance staircase revealed by the quantum point contact inserted in the one
of the arms of the double-slit ring are found to result from the interplay of
the spontaneous spin polarization and the Rashba spin-orbit interaction.
Secondly, the quantum scatterers connected to two one-dimensional leads and the
quantum point contact inserted are shown to define the amplitude and the phase
of the Aharonov-Bohm and the Aharonov-Casher conductance oscillations.Comment: 8 pages, 5 figure
Superconductivity in silicon nanostructures
We present the findings of the superconductivity observed in the silicon
nanostructures prepared by short time diffusion of boron on the n-type Si(100)
surface. These Si-based nanostructures represent the p-type ultra-narrow
self-assembled silicon quantum wells, 2nm, confined by the delta - barriers
heavily doped with boron, 3nm. The EPR and the thermo-emf studies show that the
delta - barriers appear to consist of the trigonal dipole centres, which are
caused by the negative-U reconstruction of the shallow boron acceptors. Using
the CV and thermo-emf techniques, the transport of two-dimensional holes inside
SQW is demonstrated to be accompanied by single-hole tunneling through these
negative-U centres that results in the superconductivity of the delta -
barriers. The values of the correlation gaps obtained from these measurements
are in a good agreement with the data derived from the temperature and magnetic
field dependencies of the magnetic susceptibility, which reveal a strong
diamagnetism and additionally identify the superconductor gap value.Comment: 4 pages, 6 figures, presented at the 4th International Conference on
Vortex Matter in Superconductors, Crete, Greece, September 3-9, 200
Spin interference in silicon one-dimensional rings
We present the first findings of the spin transistor effect caused by the
Rashba gate-controlled ring embedded in the p-type self-assembled silicon
quantum well that is prepared on the Si (100) surface. The coherence and phase
sensitivity of the spin-dependent transport of holes are studied by varying the
value of the external magnetic field and the gate voltage that are
perpendicular to the plane of the double-slit ring. Firstly, the quantum
scatterers connected to two one-dimensional leads and the quantum point contact
inserted in the one of the arms of the double-slit ring are shown to define the
amplitude and the phase of the Aharonov-Bohm and the Aharonov-Casher
conductance oscillations. Secondly, the amplitude and phase sensitivity of the
0.7 feature of the hole quantum conductance staircase revealed by the quantum
point contact inserted are found to result from the interplay of the
spontaneous spin polarization and the Rashba spin-orbit interaction.Comment: 2 pages, 2 figures, presented at the 5th International Conference on
Strongly Correlated Electron Systems, SCES'05, Vienna, Austria, 26-30 July,
200
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