Ac susceptibility studies of a superconducting gallium nanocomposite: Crossover in the upper critical field line and activation barriers

M. K. Lee, E. V. Charnaya, Cheng Tien, L. J. Chang, Yu A. Kumzerov

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Ac magnetization measurements were carried out for a gallium nanocomposite consisted of a metal loaded porous glass with 3.5 nm pore size to study dynamics in the vortex system and H-T diagrams. Variations of ac magnetization with temperature and bias magnetic field were obtained at different frequencies and amplitudes of ac field. Double peaks in the imaginary part of ac susceptibility associated with doubly structured real parts with distinct dependences on the amplitude of ac field were observed. Activation barriers were evaluated from variations with frequency of the upper-temperature peak in χ″ at different bias fields. The field dependence of the activation barrier followed the power law with exponents equal to 0.12 and 1.0 below and above 20 kOe, respectively. A pronounced positive curvature was observed at low magnetic fields for the Hc2(T) line with the crossover to a common negative curvature near 20 kOe, also. Both the change of the exponent in the power law for activation barriers and the crossover to the negative curvature in the upper critical field line were suggested to occur due to transition in the vortex system from the geometry restricted to space between gallium particles into more homogeneous distribution with increasing field.

Original languageEnglish
Article number113903
JournalJournal of Applied Physics
Volume113
Issue number11
DOIs
Publication statusPublished - 2013 Mar 21

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gallium
crossovers
nanocomposites
curvature
activation
magnetic permeability
exponents
vortices
magnetization
magnetic fields
diagrams
porosity
temperature
glass
geometry
metals

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

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abstract = "Ac magnetization measurements were carried out for a gallium nanocomposite consisted of a metal loaded porous glass with 3.5 nm pore size to study dynamics in the vortex system and H-T diagrams. Variations of ac magnetization with temperature and bias magnetic field were obtained at different frequencies and amplitudes of ac field. Double peaks in the imaginary part of ac susceptibility associated with doubly structured real parts with distinct dependences on the amplitude of ac field were observed. Activation barriers were evaluated from variations with frequency of the upper-temperature peak in χ″ at different bias fields. The field dependence of the activation barrier followed the power law with exponents equal to 0.12 and 1.0 below and above 20 kOe, respectively. A pronounced positive curvature was observed at low magnetic fields for the Hc2(T) line with the crossover to a common negative curvature near 20 kOe, also. Both the change of the exponent in the power law for activation barriers and the crossover to the negative curvature in the upper critical field line were suggested to occur due to transition in the vortex system from the geometry restricted to space between gallium particles into more homogeneous distribution with increasing field.",
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Ac susceptibility studies of a superconducting gallium nanocomposite : Crossover in the upper critical field line and activation barriers. / Lee, M. K.; Charnaya, E. V.; Tien, Cheng; Chang, L. J.; Kumzerov, Yu A.

In: Journal of Applied Physics, Vol. 113, No. 11, 113903, 21.03.2013.

Research output: Contribution to journalArticle

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AU - Charnaya, E. V.

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