Specific heat of low

A sensitive differential ac technique has been used to measure the specific heat of low-(Formula presented) single-crystal (Formula presented) in fields up to 7 T applied parallel to the (Formula presented) axis. In contrast to high-(Formula presented) cuprates where a magnetic field substantially broadens the resistive transition, in these low-(Formula presented) samples, the field simply shifts the transition to lower temperatures leaving its width unchanged. Our specific-heat results, however, show a quite different behavior. The superconducting anomaly is dramatically reduced in size and broadened by the field, suggesting, in analogy with other cuprates, the presence of strong thermal-fluctuation effects.