Upper critical field of Ba1−χKχBiO3 single crystal

✍ Scribed by C. Escribe-Filippini; J. Marcus; M. Affronte; H. Rakoto; J.M. Broto; J.C. Ousset; S. Askenazy

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 440 KB
• Volume: 210
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(93)90017-k

✦ Synopsis

We measured the upper critical field Hcz on Bar _XK,BiOs (0.35 <x-z 0.40) single crystal down to 2 Kin pulsed magnetic fields up to 35 T. Resistive transitions in the magnetic field systematically shift as the temperature decreases and thepH curves saturate for high enough magnetic field strength. The initial slope of the upper critical field (dHJdT), is -0.5 T/K. As temperature decreases, the H,,-T curve shows an upward curvature. At 2 K we find H,r=30 T, which gives a coherence length c= 33 A. Such an H,, value is almost twice as large as what one can deduce by using the standard expression He2 (0) = -0.693 T,( dHJdT) re. From the comparison with several models, we conclude that this unusual temperature dependence of HE2 can be due either to structural instability or to microscopic sample inhomogeneities.