PHYSICAL-PROPERTIES OF HGBA2CA2CU3O8 WITH T-C-APPROXIMATE-TO-133K

Several samples containing HgBa2Ca2Cu3O8+delta (Hg-1223) as the main p hase have been investigated. Specific-heat C-p(T) data measured on our samples with the largest volume fraction Hg-1223 (approximate to 60%) show a distinct discontinuity Delta C-p(T)(c) approximate to 27 mJ/mo le K-2 at T-c. From measurements of the reversible magnetization M(H,T ) in the mixed state, we obtain approximate values for the London pene tration depth lambda(ab)(0), for the coherence length xi(ab)(0), for t he lower and the upper critical fields H-c1,H-c(0) and H-c2,H-c(0), re spectively, and for the Ginzburg-Landau parameter K, valid for externa l fields H//c axis. The location of the irreversibility line in the B- T phase diagram allows us to estimate the anisotropy ratio gamma=lambd a(c)/lambda(ab), while magnetization-loop data taken in the irreversib le part of mixed state give information about the critical-current den sities j(c) to be expected in Hg-1223. Tunneling-conductance investiga tions with a scanning-tunneling microscope give a gap value Delta appr oximate to 24 meV at T = 4.2 K.