Pressure effects on resistive transition in (Cu,M)Ba2Ca3Cu4Oy (M=C,Al,Tl,Mg,Zn) superconductors

Single phase samples with the composition of (Cu,M)Ba2Ca3Cu4Oy (CuM-1234; M =C,Al,Tl,Mg,Zn) have been synthesized using high pressure technique. We hav e measured the pressure dependence of superconducting transition temperatur e (T-c) through insitu resistivity measurements up to 8 GPa for these sampl es, reproducibly. These samples indicated almost the same T-c-enhancement b y applied pressure, in spite of their different ambient T-c values. The enh ancement values of 8-10 K at 8 GPa pressure for these samples are found to be comparable to those of Hg-system and (B,C)-system.