ELECTRONIC SPECIFIC-HEAT OF TL2BA2CUO6-K TO 300-K FOR -EQUAL-TO-DELTA-GREATER-THAN-OR-EQUAL-TO-0.1(DELTA FROM 2)

Using a high-precision differential technique with a resolution of 1:1 0(4), we have measure the heat capacity of Tl2Ba2CuO6+delta over a tem perature range 2-300 K for 0 less-than-or-equal-to delta less-than-or- equal-to 0.1. Anomalies at T(c) are seen for all superconducting compo sitions measured, and the results are consistent with a temperature- a nd delta-independent normal-state electronic term gamma(n) approximate ly 0.6 mJ/g-at. K2. The samples with the larger T(c)'s exhibit strong fluctuations in their specific heat, typical of a highly anisotropic 2 D superconductor, but there is some evidence that these fluctuations b ecome weaker at T(c) falls-consistent with an increase in the coherenc e length on hole doping. At temperatures below 5 K an upturn in the da ta is observed which appears to increase in magnitude as T(c) falls, c orrelating with the increase in the Curie term of published susceptibi lity data.