arXiv subjects

N. T. Bagraev

Publications and source records attributed to N. T. Bagraev.

At least 19 recordsLinked to original sources

arXiv2026

Meissner-Ochsenfeld effect in semiconductor nanostructures with negative-U shells

The Meissner-Ochsenfeld effect is demonstrated for the first time at room temperature. The diamagnetic response of a silicon nanostructure with edge channels covered by chains of negative U dipole boron centers is studied when put in (removed from) an external magnetic field. Measurements of the diamagnetic response were carried out by recording the values of magnetization and generation currents. There is good agreement between the results of measurements of the generated internal magnetic field obtained using a ferroprobe and recording the EMF induced by the occurrence of generation currents in an external magnetic field, which determines the conditions of the mechanism of the nondissipative transport in the edge channels at room temperature, which is caused by their interactions with single carriers through negative U dipole boron centers. The interrelation of the magnetization hysteresis and the magnitude of the EMF induced by the occurrence of generation currents indicates the possibilities of the electrical registration of the Meissner-Ochsenfeld effect in nanostructures manufactured within the framework of the Hall geometry.

cond-mat.mes-hall↗

arXiv2026

Andreev terahertz radiation generators

The electrical, magnetic and optical properties of edge channels consisting of spin circuits that contain single carriers in nanostructures of silicon, silicon carbide and cadmium fluoride are investigated. It is demonstrated that due to the presence of chains of negative-U dipole centers at the boundaries of the spin circuits, the latter are Andreev molecules for generating terahertz radiation.

cond-mat.mes-hall↗

arXiv2026

Optical detection of the quantum Hall effect in silicon nanostructures

Electroluminescence spectra of a silicon nanostructure with edge channels covered by chains of dipole centers with negative correlation energy are demonstrated. The presence of such chains provides conditions for nondissipative transport of single charge carriers at high temperatures up to room temperature. Due to the suppression of the electron-electron interactions, the macroscopic quantum phenomena such as Shubnikov - de Haas oscillations and the quantum staircase of Hall resistance are consistent with the positions of the spectral peaks of the detected electroluminescence. The obtained results are considered in the framework of Faraday electromagnetic induction, which indicates that Landau quantization leads to the emergence of induced irradiation similar to Josephson and Andreev generation. Moreover, the detected maxima in the spectral characteristics correspond to odd fractional values of the resistance quantum staircases, while the dips in the electroluminescence spectra are observed at even fractional values of the resistance quantum ladder, which is due to the increased formation of composite bosons and fermions, respectively.

cond-mat.mes-hall↗

arXiv2023

Terahertz emission from silicon carbide nanostructures

For the first time, electroluminescence detected in the middle and far infrared ranges from silicon carbide nanostructures on silicon, obtained in the framework of the Hall geometry. Silicon carbide on silicon was grown by the method of substitution of atoms on silicon. The electroluminescence from the edge channels of nanostructures is induced due to the longitudinal drain-source current. The electroluminescence spectra obtained in the terahertz frequency range, 3.4, 0.12 THz, arise due to the quantum Faraday effect. Within the framework of the proposed model, the longitudinal current induces a change in the number of magnetic flux quanta in the edge channels, which leads to the appearance of a generation current in the edge channel and, accordingly, to terahertz radiation.

cond-mat.mes-hall↗

arXiv2023

Registration of terahertz irradiation with silicon carbide nanostructures

The response to external terahertz (THz) irradiation from the silicon carbide nanostructures prepared by the method of substitution of atoms on silicon is investigated. The kinetic dependence of the longitudinal voltage is recorded at room temperature by varying the drain-source current in the device structure performed in a Hall geometry. In the frameworks of proposed model based on the quantum Faraday effect the incident radiation results in the appearance of a generated current in the edge channels with a change in the number of magnetic flux quanta and in the appearance of features in the kinetic dependence of the longitudinal voltage. The generation of intrinsic terahertz irradiation inside the silicon carbide nanostructures is also revealed by the electrically-detected electron paramagnetic resonance (EDEPR) measured the longitudinal voltage as a function of the magnetic field value.

physics.app-ph↗

arXiv2023

Room-temperature quantum oscillations of static magnetic susceptibility of silicon-carbide epitaxial layers grown on a silicon substrate by the method of the coordinated substitution of atoms

The article presents the results of measurement and analysis of the field dependences of the static magnetic susceptibility of thin epitaxial silicon carbide films grown on the (110) surface of single-crystal silicon by the method of the coordinated substitution of atoms. In weak magnetic fields, the occurrence of two quantum effects at room temperature was experimentally found: the hysteresis of the static magnetic susceptibility and, in the field dependences, quantum Aharonov-Bohm oscillations of the static magnetic susceptibility. The simultaneous occurrence of these effects is a consequence of two- and one-particle interference of charge carriers (two-dimensional holes) on microdefects consisting of dipole centers with negative correlation energy (negative-U dipole centers).

cond-mat.mtrl-sci↗

arXiv2022

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.

cond-mat.mes-hall↗

arXiv2020

Terahertz Response of Biological Tissue for Diagnostic and Treatment in Personalized Medicine

A spectrometer based on silicon nanosandwiches (SNS) is proposed for problems of personalized medicine. SNS structures exhibit properties of terahertz (THz) emitter and receiver of the THz response of biological tissue. Measurements of the current-voltage curves of the SNS structure make it possible to analyze the spectral composition of the THz response of biological tissue and determine relative contributions of various proteins and amino acids contained in the structure of DNA oligonucleotides and the corresponding compounds. Evident advantages of the proposed method are related to the fact that the THz response can be directly obtained from living biological tissue and, hence, used for express analysis of the DNA oligonucleotides. Tests of several control groups show that the further analysis of the specific features of the spectral peaks of the SNS current-voltage curves is of interest for methods of personalized diagnostics and treatment.

physics.med-ph↗

arXiv2020

Terahertz resonance response of biological tissue placed on a silicon nanostructure

We present a method for the measurements of the tetrahertz (THz) resonance response of DNA oligonucleotides deposited on a silicon nanosandwich (SNS). It is shown that the SNS device can be used to generate a THz resonance response within living biotissue. The technique we propose measures changes of the longitudinal conductance and the lateral voltage with the SNS device in a Hall geometry. The mechanism of the THz response is discussed, with a model of the generation of Shapiro steps. The THz resonance response from living biotissues will aid the diagnosis of oncological disease and, in general, form the basis of a rapid diagnosis in practical medicine.

physics.app-ph↗

arXiv2020

High Temperature Quantum Kinetic Effect in Silicon Nanosandwiches

The negative-U impurity stripes confining the edge channels of semiconductor quantum wells are shown to allow the effective cooling inside in the process of the spin-dependent transport, with the reduction of the electron-electron interaction. The aforesaid promotes also the creation of composite bosons and fermions by the capture of single magnetic flux quanta on the edge channels under the conditions of low sheet density of carriers, thus opening new opportunities for the registration of the quantum kinetic phenomena in weak magnetic fields at high temperatures up to the room temperature. As a certain version noted above we present the first findings of the high temperature de Haas-van Alphen, 300K, quantum Hall, 77K, effects as well as quantum conductance staircase in the silicon sandwich structure that represents the ultra-narrow, 2 nm, p-type quantum well (Si-QW) confined by the delta barriers heavily doped with boron on the n-type Si (100) surface.

cond-mat.mes-hall↗

arXiv2020

Phase control of the fractional conductance of silicon nanosandwich-structures

We present the experimental data of the electric features of the silicon nanosandwichstructures obtained by silicon planar technology in the frameworks of the Hall geometry that represent the ultra-shallow silicon quantum well of 2 nm wide that are confined by delta-barrier heavily doped with boron, which create the edge channels used as the phase controllers of electric signals. The formation of the negative-U dipole boron centers, which appear to confine the edge channels, results in the effective mass dropping and corresponding reduction of the electron-electron interaction thereby giving rise to the macroscopic quantum phenomena at high temperatures up to room temperature. The phase control of the longitudinal conductance is observed by changing either the magnitude of the source-drain current or the voltage applied to the external gate of the silicon nanosandwiches within the quantum Faraday effect.

cond-mat.mes-hall↗

arXiv2016

Room temperature de Haas - van Alphen effect in silicon nanosandwiches

The negative-U impurity stripes confining the edge channels of semiconductor quantum wells are shown to allow the effective cooling inside in the process of the spin-dependent transport. The aforesaid promotes also the creation of composite bosons and fermions by the capture of single magnetic flux quanta on the edge channels under the conditions of low sheet density of carriers, thus opening new opportunities for the registration of the quantum kinetic phenomena in weak magnetic fields at high temperatures up to the room temperature. As a certain version noted above we present the first findings of the high temperature de Haas-van Alphen, 300K, and quantum Hall, 77K, effects in the silicon sandwich structure that represents the ultra-narrow, 2 nm, p-type quantum well (Si-QW) confined by the delta barriers heavily doped with boron on the n-type Si (100) surface. These data appear to result from the low density of single holes that are of small effective mass in the edge channels of p-type Si-QW because of the impurity confinement by the stripes consisting of the negative-U dipole boron centers which seems to give rise to the efficiency reduction of the electron-electron interaction.

cond-mat.mes-hall↗

arXiv2014

Conductance matrix of multi terminal semiconductor devices with edge channels

This paper presents a method for determining the conductance matrix of multi terminal semiconductor structures with edge channels. This method appears to be applied within frameworks of the ordinary Landauer - uttiker formalism for the carrier transport analysis in the regime of both the quantum Hall Effect and the quantum spin Hall Effect. The proposed method proves to take into account principally the contribution of the probes resistance in the formation of the matrix conductance elements. Finally, the possibilities of the practical application of this method to develop new versions of analog cryptographic devices are discussed.

cond-mat.mes-hall↗

arXiv2012

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 δ-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.

cond-mat.mes-hall↗

arXiv2011

Circularly polarized electroluminescence from silicon nanostructures heavily doped with boron

The circularly polarized electroluminescence (CPEL) from silicon nanostructures which are the p-type ultra-narrow silicon quantum well (Si-QW) confined by δ-barriers heavily doped with boron, 5 10^21 cm^-3, is under study as a function of temperature and excitation levels. The CPEL dependences on the forward current and temperature show the circularly polarized light emission which appears to be caused by the exciton recombination through the negative-U dipole boron centers at the Si-QW δ-barriers interface.

cond-mat.mes-hall↗

arXiv2009

EDEPR of impurity centers embedded in silicon microcavities

We present the first findings of the new electrically-detected EPR (EDEPR) technique which reveal different shallow and deep centers without using the external cavity as well as the hf source and recorder, with measuring the only magnetoresistance of the Si-QW confined by the superconductor delta-barriers.

cond-mat.mes-hall↗

arXiv2009

Spin Transistor and Quantum Spin Hall Effects in CdBxF2-x - p-CdF2 - CdBxF2-x Sandwich Nanostructures

Planar CdBxF2-x - p-CdF2 - CdBxF2-x sandwich nanostructures prepared on the surface of the n-type CdF2 bulk crystal are studied to register the spin transistor and quantum spin Hall effects. The current-voltage characteristics of the ultra-shallow p+-n junctions verify the CdF2 gap, 7.8 eV, and the quantum subbands of the 2D holes in the p-type CdF2 quantum well confined by the CdBxF2-x delta-barriers. The temperature and magnetic field dependencies of the resistance, specific heat and magnetic susceptibility demonstrate the high temperature superconductor properties for the CdBxF2-x delta-barriers. The value of the superconductor energy gap, 102.06 meV, determined by the tunneling spectroscopy method appears to be in a good agreement with the relationship between the zero-resistance supercurrent in superconductor state and the conductance in normal state at the energies of the 2D hole subbands. The results obtained are evidence of the important role of the multiple Andreev reflections in the creation of the high spin polarization of the 2D holes in the edged channels of the sandwich device. The high spin hole polarization in the edged channels is shown to identify the mechanism of the spin transistor and quantum spin Hall effects induced by varying the top gate voltage, which is revealed by the first observation of the Hall quantum conductance staircase.

cond-mat.mes-hall↗

arXiv2008

Superconductivity in Silicon Nanostructures

We present the findings of the superconductivity in the silicon nanostructures prepared by short time diffusion of boron after preliminary oxidation of the n-type Si (100) surface. These Si-based nanostructures represent the p-type high mobility silicon quantum well (Si-QW) confined by the delta - barriers heavily doped with boron. The ESR studies show that the delta - barriers appear to consist of the trigonal dipole centers, B(+)-B(-), which are caused by the negative-U reconstruction of the shallow boron acceptors, 2B(0)=>B(+)-B(-). The temperature and magnetic field dependencies of the resistance, thermo-emf, specific heat and magnetic susceptibility demonstrate that the high temperature superconductivity observed seems to result from the transfer of the small hole bipolarons through these negative-U dipole centers of boron at the Si-QW - delta - barrier interfaces. The value of the superconductor energy gap obtained is in a good agreement with the data derived from the oscillations of the conductance in normal state and of the zero-resistance supercurrent in superconductor state as a function of the bias voltage. These oscillations appear to be correlated by on- and off-resonance tuning the two-dimensional subbands of holes with the Fermi energy in the superconductor delta - barriers. Finally, the proximity effect in the S- Si-QW -S structure is revealed by the findings of the multiple Andreev reflection (MAR) processes and the quantization of the supercurrent.

cond-mat.supr-con↗