SUPERCONDUCTIVITY IN THE LAYERED COMPOUND 2H-TAS2

The layered compound 2H-TaS2 is one of the typical materials which lead to charge density waves. However, much less information is available on the superconducting properties of this compound. The Meissner effect in 2H-TaS2 was studied systematically with special emphasis on low-d.c. applied fields. The susceptibility chi = M/H is quite weak and the value of chi is less than -8.0 x 10(-3) emu cm-3 above 0.4 K, at least 10 times smaller than the magnitude for perfect diamagnetism. A transition occurs over a rather wide temperature range. An indication of diamagnetism appears around 1.5 K which is much higher than the value of 0.8 K reported as the transition temperature in the earlier literature. The magnetization curves depart from linearity at fields less than 2.0 Oe at 0.4 K, which implies that the lower critical field H(cl) of 2H-TaS2 is extremely small.