The influence of crystal lattice disorder on electronic, superconducting and magnetic properties of thin metal films and bulk materials

● The change of character of hopping conduction in weakly coupled granulated system under the superconducting transition is found. It is found that the behavior of hopping conduction is governed by superconducting energy gap, which in this case play the role of dielectric gap [1, 2].

● The main causes of reentrant superconductivity effects in inhomogeneous systems (granulated and ultra thin non-uniform films) have been found: a) competition of activated tunneling of Cooper pairs and one particle excitations (which is the case in granulated and island films) and b) the influence of quantum phase fluctuations of electron wave function in the system of coupled Jozefson junctions with essential influence of dissipative processes in contact region (in ultra thin non-uniform films [3, 4].

● The influence of crystal lattice disorder on magnitude and temperature dependence of inelastic electron scattering has been studied [5, 6].

● The study of structural and phase inhomogeneities on superconducting and magnetic propertiesof metals [4, 7-15].

● It is found that the resistive transitions to superconducting state in ruthenocuprates RuSr2Gd1.5Ce0.5Cu2O10-d are determined by inhomogeneous granulated structure of the samples and characterized by intra- (Tc0) and inter- (Tcg) granular superconducting temperatures. A distinct jump in the temperature dependence of heat capacity C(T) corresponds to the intragranular temperature of superconducting transition TC0 » 37.5 K. For the temperatures below 20 K the thermal capacity reveals a Schottky-like anomaly that may be explained by splitting of the main term 8S7/2 of paramagnetic Gd3+ ions by external and internal magnetic fields [12-13].

● It is shown that the transport properties of ultrathin quench-condensed Au films near the thickness controlled metal-insulator transition at low temperatures can simultaneously manifest one-dimensional (1D) and two-dimensional (2D) quantum interference effects of weak localization and electron-electron interaction, as a result of inhomogeneous electron transport [16].

1. Belevtsev B.I., Komnik Yu.F., Fomin A.V. Superconductivity effects in indium granulated films in conditions of strong electron localization // Fiz. Nizk. Temp., 11, No.11, 1143 (1985).
2. Belevtsev B.I., Komnik Yu.F., Fomin A.V.  Superconductivity effects near the metal-insulator transition in granular indium films // J. Low Temp. Phys., 69(5-6), 401-417 (1987).
3. Belevtsev B.I., Komnik Yu.F., Fomin A.V. Reentrant phenomena in superconductivity of ultrathin amorphous bismuth-films // J. Low Temp. Phys., 75(5-6), 331-347 (1989).
4. Belevtsev B.I. Superconductivity and electron localization in disordered 2-dimensional metal systems // Physics-Uspekhi, 33, No. 1, 36-54 (1990).
5. Komnik Yu.F., Kashirin V.Yu., Belevtsev B.I., Beliayev E.Yu. Temperature variation of the time of inelastic electron relaxation in disordered bismuth films // Phys. Rev. B, 50, No.20, 15298-15303 (1994).
6. Belevtsev B.I., Komnik Yu.F., Beliayev E.Yu. Electron relaxation in disordered gold films // Phys. Rev. B., 58, No.12, 8079-8086 (1998).
7. Belevtsev B.I., Volchok I.V., Dalakova N.V., Dotsenko V.I., Ivanchenko L.G., Kuznichenko A.V., Logvinov I.I. Effect of gamma-irradiation on superconductivity in polycrystalline YBa₂Cu₃O_{(7- d)} // Phys. Status Solidi A-Appl. Res, 181 (2), 437-450 (2000).
8. Belevtsev B.I., Krasovitsky V.B., Bobkov V.V., Naugle D.G., Rathnayaka K.D.D., Parasiris A. Influence of high-energy electron irradiation on properties of La_1-xCa_xMnO₃ (x≈1/3) films // Eur. Phys. J., B 15(3), 461-467 (2000).

9. Belevtsev B. I., Beliayev E. Yu., Naugle D. G., Rathnayaka K. D. D., Anatska M. P., and Felner I., Granular superconductivity in polycrystalline ruthenocuprate RuSr2(Gd1.5Ce0.5) Cu2O10-d: magnetoresistive and magnetization studies, J. Phys.: Condens. Matter. 19, 036222 (13 pages) (2007).
10.  Belevtsev B. I., Naugle D. G., Rathnayaka K. D. D., Parasiris A., Fink-Finowicki J., Extrinsic inhomogeneity effects in magnetic, transport and magnetoresistive properties of La1-xCaxMnO3 (x ≈ 0.33) crystal prepared by the floating zone method", Physica B, 355, pp 341-351 (2005).
11. Belevtsev B. I., Dalakova N. V., Osmolowsky M. G., Beliayev E. Yu., Selutin A. A., Transport and magnetotransport properties of cold-pressed CrO2 powder, prepared by hydrothermal synthesis, Journal of Alloys and Compounds, 479 (2009) 11–16.
12. Naugle D.G., Rathnayaka K.D.D., Krasovitsky V.B., Belevtsev B.I., Anatska M.P., Agnolet G., Felner I. Transport, thermal, and magnetic properties of RuSr2Gd1.5Ce0.5Cu2O10-d, a magnetic superconductor // J. Appl. Phys. 99, 08M501-08M503 (2006).

13. Belevtsev B. I., Beliayev E. Yu., Naugle D. G., Rathnayaka K. D. D., Anatska M. P., and Felner I., Granular superconductivity in polycrystalline ruthenocuprate RuSr2(Gd1.5Ce0.5) Cu2O10-d: magnetoresistive and magnetization studies, J. Phys.: Condens. Matter. 19, 036222 (13 pages) (2007).
14. Belevtsev B. I., Naugle D. G., Rathnayaka K. D. D., Parasiris A., Fink-Finowicki J., Extrinsic inhomogeneity effects in magnetic, transport and magnetoresistive properties of La1-xCaxMnO3 (x ≈ 0.33) crystal prepared by the floating zone method", Physica B, 355, pp. 341-351 (2005).
15. Belevtsev B. I., Dalakova N. V., Osmolowsky M. G., Beliayev E. Yu., Selutin A. A., Transport and magnetotransport properties of cold-pressed CrO2 powder, prepared by hydrothermal synthesis, Journal of Alloys and Compounds, 479 (2009) 11–16.
16. Belevtsev B.I., Beliayev E.Yu., Kolesnichenko Yu.A. 1D and 2D quantum interference effects in electron transport in Au film // Int. J. Mod. Phys. B, 27, 1350026 (2013).