The Upper Critical Field of the High Tc Superconductor Ba_0.6K_0.4BiO_3
Abstract
Extensive measurements of the magnetization of several superconducting single crystal samples of Ba_0.6K_0.4BiO3 have been made using SQUID and force magnetometry at temperatures ranging between 1.3 and 350 K and in magnetic fields from near zero to 27 T. Hysteresis curves of magnetization versus field allow a determination of the thermodynamic critical field, the reversibility field, the lower and upper critical fields, and the Ginzburg-Landau parameter. The results from the high Tc crystals show high critical fields, and interesting thermodynamic properties. All critical fields are higher than have been previously observed. From our measurements and measurements of the specific heat across T_c, we conclude that the thermodynamic order of the superconducting transition may be higher than two. A <A HREF=http://hallmac.magnet.fsu.edu/personal/professional.html#Publ ications>preprint</A> of this paper is available.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1998
- Bibcode:
- 1998APS..MAR.X3702H