Reversible magnetization and torques in anisotropic high-. kappa. type-II superconductors
- Ames Laboratory-U.S. Department of Energy and Department of Physics, Iowa State University, Ames, Iowa 50011 (USA)
The reversible magnetization of anisotropic high-{kappa} type-II superconductors in an applied field {bold H} of arbitrary orientation with respect to the principal axes of the sample is considered in the framework of the Ginzburg-Landau theory with an anisotropic effective mass. We examine the procedure of obtaining the free-energy density {ital F} from its corresponding expression in the isotropic case by simply replacing the Ginzburg-Landau parameter {kappa} by a {tilde {kappa}} that depends on the orientation of {bold H} relative to the principal axes. This procedure is valid when {bold H} is along one of the principal axes for arbitrary values of {ital H} between {ital H}{sub {ital c}1} and {ital H}{sub {ital c}2} and is also valid to a good approximation when {bold H} is not along one of the principal axes, but only when {ital H}{much gt}{ital H}{sub {ital c}1}. Because of the dependence of {ital F} on the orientation of {bold H}, when {bold H} is not parallel to one of the principal axes, the average magnetic-flux density {bold B} is not parallel to {bold H}, and a torque associated with the transverse magnetization exists, tending to orient the sample so that the value of {tilde {kappa}} is the largest. Expressions for the magnetization and the torque are obtained from a variational model that permits the analytic calculation of {ital F} in the Ginzburg-Landau regime including, in addition to the supercurrent kinetic energy and the magnetic-field energy, the kinetic-energy and the condensation-energy terms arising from suppression of the order parameter in the vortex core.
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5661899
- Journal Information:
- Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 43:10; ISSN 0163-1829; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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