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Study of  electrodynamic and thermodynamic properties of low-dimensional systems

2013
Department: Лаборатория физики низкоразмерных систем
The project has been carried out as part of the HSE Program of Fundamental Studies.

Object of Research: low-dimensional systems including nanotubes, quasi-one-dimentional Haldane system (Y1-xNdx) 2BaNiO5, deuterated heterostructure Ti/TiO2: Dx and Pd/PdO: Dx.

Goal of Research: modelling of the electrophysical and thermodynamic parameters of the nanotube; revealing of the behavior of the magnetic subsystems and estimating the parameters of their interaction in a Haldane system (Y1-xNdx) 2BaNiO5; refinement of the model of  electron transport in the thick and thin layers of materials; creating compact general and specific theoretical models of electrodynamics; revealing of the physical nature of the possible increase in the  nuclear fusion reaction probability  in deuterated heterostructures.

Empirical Base of Research:

-  a theoretical study of the influence of a magnetic field on the electrical and thermodynamic properties of nanotubes, as well as a numerical and analytical study of the thermodynamic properties of magnetized superconducting quantum cylinder was performed  by using methods of quantum field theory and quantum statistical physics;

- the magnetic properties of (Y1-xNdx)2BaNiO(x =1, 0.15) were investigated by means of specific heat, magnetic susceptibility, magnetization, and spectroscopic measurements. Polycrystalline samples of (Y1–xNdx)2BaNiO5 with x = 1.0 and 0.15 were synthesized through solid state reactions. Temperature dependences of the magnetic susceptibility in zero-field-cooled  and field-cooled regimes were measured in the magnetic field of 0.01T at temperatures between 1.8 and 350 K using a MPMS-XL5 SQUID magnetometer (Quantum Design). Temperature dependences of the specific heat were studied in the temperature range 0.4¸ 300K by means of a relaxation method in a Physical Property Measurement System (Quantum Design). The field dependences of the magnetization were measured at different temperatures in a magnetic field of up to 15 T by means of a vibrating sample magnetometer. Optical measurements in the spectral range 10000–15000 cm–1 were performed using a Fourier spectrometer BOMEM DA3.002; the analysis of experimental results was carried out using quantum mechanical methods.

- the transport properties of electrons in thick and thin layers of substances were investigated using the model of the generalized diffusion;

- the experimental research  of the  stimulation of the DD- reaction yields from the  Ti/TiO2: Dx and Pd / PdO: Dx heterostructures by beams of H + and Ne + ions in energy range 10 – 25 keV was carried out with GELIS installation.

- the emission of neutron bursts in the process of high-voltage discharge in air was observed by means of experiments carried out at an average electric field strength  of~1 MV/m and discharge current of~10 kA. The experiments were carried out with a high current electron beam accelerator ERG, reconstructed for studying the high-voltage discharge in air.

Results of Research:

- it was found that for nanotubes, in the case of an isotropic phonon spectrum, the contribution of electron-phonon scattering into quantum cylinder resistivity changes its temperature dependence from linear behavior at high temperatures to cubic at moderately low temperatures;

- it was found that the change of the Aharonov-Bohm parameter is accompanied by an oscillatory change in the conductivity of the nanotube, and the amplitude of the oscillations increases significantly when the effects of the size limitations of phonons are taken into account;

- for magnetized superconducting quantum cylinders, closed-form expressions for critical temperature, the free energy, the capacity jump, and the magnetization difference between the superconducting and normal phases as functions of the nanotube parameters are obtained in limit cases;

- it was found that the antiferromagnetic ordering in quasi-one-dimensional magnet (Y1-xNdx)2BaNiO5   occurs at 47 K and 13 K in the compounds with x=1 and x =0.15, respectively;

- the magnetic contribution of the neodymium subsystem (Y1-xNdx)2BaNiO5   into specific heat, magnetic susceptibility and  magnetization  using data of the spectroscopic measurements was estimated. We showed that macroscopic magnetic and thermodynamic properties cannot be accounted for without considering the Nd-Nd interactions.  The parameters of both Nd – Ni and Nd - Nd interactions were estimated;

- it was found that the nickel subsystem in magnetically ordered (Y1-xNdx)2BaNiOcompounds have the same properties as in a disordered Haldane-gap Y2BaNiO5 system;

- it is suggested that a model describing the behavior of the magnetization as a function of the magnetic field which takes into account that (1 ) a strong magnetic anisotropy Nd3+ ion prevents the magnetic moments of neodymium from deviating from the c-axis even in the presence of a strong external magnetic field, (2) a strong antiferromagnetic exchange within the chain (J ~ 280K) prevents the magnetic moments of nickel ions to change their direction in relation to each other under the influence of an external field, (3 ) the breaks in the nickel chains which are always present in the sample give a contribution into the magnetization and lead to change of the magnetic moment of nickel ion;

- the analytical model of the generalized diffusion of fast particles was formulated. It provides the possibility of calculating, with precision of 10-30% of the mean free path along the coordinate of the accelerated electrons and photons in a wide range of particle energies and media parameters, as well as estimating the distribution of the mean free paths, of the energy input, and the fast particle relaxation time for a wide range of cascade degradation processes;

- the principle difference of fast particles beams transport in thin and thick layers of substance, as well as features of beam reflection from the scattering substance are shown. The maximum thickness of the thin layer in which the inhibition of fast particles occurs without the curvature of the trajectory was calculated. We found that the thickness of the average five-fold path weakens the flow of fast particles by many orders;

- the compact Lorentz transformation for Coulomb's force was completed, indicating that the magnetic force is a relativistic correction to the Coulomb's force. The fact that the relativistic Coulomb law is the basic law both of electrostatics and electrodynamics was demonstrated;

- it was found that the presence of significant amplification effects of the  DD-reaction yields from the  Ti/TiO2: Dx and Pd / PdO: Dx heterostructures by beams of H + and Ne + ions in energy range 10 – 25 keV. The screening potential estimated at the experimental conditions is Ue = 897 eV for Pd / PdO: Dx heterostructure, and is Ue = 796 eV for Ti / TiO: Dx heterostructure;

- the emission of neutron bursts in the process of high-voltage discharge in air was observed at an average electric field strength  of ~1 MV/ mand discharge current of ~10 kA. The neutrons are emitted within the range from  thermal energies up to energies above 10 MeV and with an average flux density of 106 – 107  per shot. It was found that neutron emission occurs at the very beginning of the discharge and strongly correlates with x-ray radiation.

Level of implementation, recommendations  on implementation or outcomes of the implementation of Results: the results of scientific research into the electrodynamic and thermodynamic properties of the nanotubes and the low-dimensional magnets can be used to design the elements for nanoelectronics. Research of the enhancement effects of the  DD-reaction yields from the  Ti/TiO2: Dx and Pd / PdO: Dx heterostructures can be used for the selection of materials in which the enhancement of nuclear reactions are most pronounced, which will allow to determine the prospects of their application in future installations of controlled nuclear fusion .

Field of application: the results of the research can be used to further study the fundamental properties of low-dimensional systems. Furthermore, the results can also be used in the courses of Masters programs.

Publications:


Эминов П. А., Сезонов Ю. И., Гордеева С. Электропроводнось нанотрубок в магнитном поле // В кн.: Труды XXIII Международной конференции "Радиационная физика твердого тела" (Севастополь, 8 июля - 13 июля 2013) / Науч. ред.: Г. Г. Бондаренко. М. : ФГБНУ "НИИ ПМТ", 2013. С. 432-439.
Никеров В. А. Каскадно-деградационные процессы. Часть 2. Каскадно-деградационные процессы: примеры // Прикладная физика и математика. 2013. № 5. С. 47-73.
Конов К. И., Никеров В. А. Пробеги электронов в толстых и тонких слоях веществ в модели обобщенной диффузии // В кн.: Труды XXIII Международной конференции "Радиационная физика твердого тела" (Севастополь, 8 июля - 13 июля 2013) / Науч. ред.: Г. Г. Бондаренко. М. : ФГБНУ "НИИ ПМТ", 2013. С. 110-116.
Popova E., Klimin S. A., Popova M. N., Vasil’ev A. N., Klingeler R., Tristan N., Büchner B. Magnetic properties of quasi-one-dimensional antiferromagnets (Y 1-xNdx)2BaNiO5 (x=1, 0.15) // Journal of Magnetism and Magnetic Materials. 2013. Vol. 331. P. 133-139. doi
О.Д. Далькаров, Багуля А., Козлов Ю., Негодаев М., Русецкий А., Чубенко А., . Щепетов А. Стимулирование выходов DD-реакций из гетероструктуры Ti/TiO2:Dx пучками ионов Н+ и Ne+ на установке ГЕЛИС // Краткие сообщения по физике Физического института им. П.Н. Лебедева Российской Академии Наук. 2013. № 11. С. 3-8.
О.Д.Далькаров, Багуля А., Козлов Ю., Негодаев М., Русецкий А., Чубенко А., Щепетов А. Исследование стимулирования выходов DD-реакций из гетероструктуры Pd/PdO:Dx пучками ионов Н+ и Ne+ на установке ГЕЛИС // Краткие сообщения по физике Физического института им. П.Н. Лебедева Российской Академии Наук. 2013. № 10. С. 15-18.
O. D. Dalkarov, Agafonov A., Bagulya A., Negodaev M. A., Oginov A., Rusetskiy A. S., Ryabov V. A., Shpakov K. Observation of Neutron Bursts Produced by Laboratory High-Voltage Atmospheric Discharge // Physical Review Letters. 2013. Vol. 111. P. 115003-115007 . doi
Eminov P. A., Sezonov Yu.I. Thermodynamic Properties of Superconducting Magnetized Nanotubes // Nanopages. 2013. No. 8. P. 1-7. doi
Попова Е.А., Климин С., Попова М., Klingeler R., Tristan N., Büchner B., Васильев А. Особенности поведения магнитных подсистем в Nd2BaNiO5 // Журнал экспериментальной и теоретической физики. 2014. Т. 145. № 4. С. 697-708. doi