DIRECT MEASUREMENT OF ELECTRON SPIN-LATTICE RELAXATION-TIME OF PARAMAGNETIC CENTERS AND NONLINEAR MODULATED RESPONSES IN HTSC

被引:3
作者
ATSARKIN, VA
DEMIDOV, VV
VASNEVA, GA
NOGINOVA, NE
机构
[1] Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Moscow, 103907
关键词
D O I
10.1007/BF03162581
中图分类号
O64 [物理化学(理论化学)、化学物理学]; O56 [分子物理学、原子物理学];
学科分类号
070203 ; 070304 ; 081704 ; 1406 ;
摘要
The report consists of two parts. 1. The method is described to measure directly the elec tron spin-lattice relaxation time T-1 in high-T-c superconductors (HTSC). The technique is based on registering the oscillating longitudinal spin magnetization while saturating the EPR line by an amplitude-modulated microwave field. The T-1 values of the Cu2+ centers in YBa2Cu3O6+x (x = 0.24-0.9) and Y2BaCuO5 materials are measured and found to be about 1.4 . 10(-9) s independently of x and temperature in the range 77-300 K. Besides much longer relaxation is displayed in degradated malerials. The data obtained can be considered as an argument in favor of the ''green-phase'' origin of the ''high-temperature'' EPR spectra in the YBaCuO HTSCs. 2. Non-linear responses of the microwave (10(10) Hz) and rf (10(5)-10(7) Hz) absorption in HTSC materials to low-frequency magnetic modulation are studied and found to be quite different in the two frequency ranges. It is shown that at microwaves the effect is caused by non-linear interaction with shielding supercurrents whereas at lower frequencies it is due to jumps of fluxons over potential barriers. The models developed take into account the Josephson weak links and the thermo-assisted nux creep.
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页码:1 / 10
页数:10
相关论文
共 17 条
  • [1] EPR STUDY OF POLYCRYSTALLINE SUPERCONDUCTORS WITH YBA2CU3O7 STRUCTURE
    ALEKSEEVSKII, NE
    MITIN, AV
    NIZHANKOVSKII, VI
    GARIFULLIN, IA
    GARIFYANOV, NN
    KHALIULLIN, GG
    KHYLBOV, EP
    KOCHELAEV, BI
    TAGIROV, LR
    [J]. JOURNAL OF LOW TEMPERATURE PHYSICS, 1989, 77 (1-2) : 87 - 118
  • [2] ALEKSEYEVSKII NE, 1988, ZH EKSP TEOR FIZ+, V94, P276
  • [3] NONLINEAR AC EFFECT AND DISSIPATION IN WEAK-LINK MEDIUM OF HIGH-TC SUPERCONDUCTORS
    ATSARKIN, VA
    DEMIDOV, VV
    NOGINOVA, NE
    VASNEVA, GA
    BUSH, AA
    [J]. PHYSICS LETTERS A, 1991, 154 (7-8) : 416 - 420
  • [4] ATSARKIN VA, 1990, PHYS CHEM TECHN, V3, P1321
  • [5] ATSARKIN VA, 1993, PISMA ESKP TEOR FIZ, V58, P103
  • [6] BARONE A, 1982, PHYSICS APPLICATIONS
  • [7] MODULATED RADIOFREQUENCY AND MICROWAVE-ABSORPTION IN SUPERCONDUCTORS WITH INTRINSIC WEAK LINKS
    DEMIDOV, VV
    NOGINOVA, NE
    [J]. SOLID STATE COMMUNICATIONS, 1992, 82 (07) : 527 - 529
  • [8] MODEL FOR FLUX CREEP IN HIGH-TC SUPERCONDUCTORS
    DEWHUGHES, D
    [J]. CRYOGENICS, 1988, 28 (10) : 674 - 677
  • [9] MECHANISMS OF FIELD-DEPENDENT MICROWAVE-ABSORPTION IN HIGH-TC CERAMIC SUPERCONDUCTORS
    DULCIC, A
    RAKVIN, B
    POZEK, M
    [J]. EUROPHYSICS LETTERS, 1989, 10 (06): : 593 - 598
  • [10] COMPARISON OF THE ESR-SPECTRA IN CERAMIC YBA2CU3O7-Y (1 GREATER-THAN Y GREATER-THAN 0) AND RELATED PHASES
    GENOSSAR, J
    SHALTIEL, D
    ZEVIN, V
    GRAYEVSKY, A
    FISHER, B
    [J]. JOURNAL OF PHYSICS-CONDENSED MATTER, 1989, 1 (47) : 9471 - 9482