A. Junod et al., SPECIFIC-HEAT UP TO 14 TESLA AND MAGNETIZATION OF A BI2SR2CACU2O8 SINGLE-CRYSTAL THERMODYNAMICS OF A 2D SUPERCONDUCTOR, Physica. C, Superconductivity, 229(3-4), 1994, pp. 209-230
A 0.25g single crystal of Bi2Sr2CaCu2O8 with a sharp superconducting t
ransition at 85 K is characterized by AC susceptibility, X-ray diffrac
tion, Meissner effect, normal-state susceptibility, magnetization in t
he mixed state, and specific heat from 1 to 300 K. The residual linear
term gammaT in the specific heat at low T is small and field indepen
dent. High-resolution (< 0.02%) adiabatic specific heat experiments pe
rformed between 0 and 14 T near T(c) show that: (a) there is no mean-f
ield specific heat jump at T(c); (b) a symmetrical logarithmic 'diverg
ence' occurs at the transition; (c) its amplitude decreases with B(-2/
3); (d) its width scales with B1/2; (e) T(c) does not depend on the fi
eld, and coincides with the crossing point of the magnetization curves
M (H,T*); (f) a crossing point C(x) (H,T(x) is found in the specific
heat 10 K below T(c); (g) the effect of a field along the CuO planes
is at least 50 times smaller than that of a field along the c axis; (h
) no transition is observed at the irreversibility line. An empirical
formula for partial Derivative (C/T)/ Partial DerivativeH that account
s for C(H,T) and M(H,T) data over a wide temperature and field range i
s proposed.