SPECIFIC-HEAT OF LOW-T-C TL2BA2CUO6+DELTA

A sensitive differential ac technique has been used to measure the spe cific heat of low-T-c single-crystal T(l)2Ba(2)CuO(6+delta)(T-c approx imate to 15 K) in fields up to 7 T applied parallel to the c axis. In contrast to high-T-c cuprates where a magnetic field substantially bro adens the resistive transition, in these low-T-c samples, the field si mply shifts the transition to lower temperatures leaving its width unc hanged. Our specific-heat results, however, show a quite different beh avior. The superconducting anomaly is dramatically reduced in size and broadened by the field, suggesting, in analogy with other cuprates, t he presence of strong thermal-fluctuation effects.