Double-step resistive superconducting transitions of indium and gallium in porous grass

We studied indium and gallium in porous glass by resistance and magnetization measurements. For indium in porous glass, a very sharp superconducting transition is observed at T-1=4.0+/-0.05 K. When a 1.5 T magnetic field is applied, there is a second transition at T(2)similar to 3.5 K. At 3.5 K, the field dependence of resistance R(H) indicates two transitions at H(c)(u)similar to 1.4 and H(c)(l)similar to 0.4 T separated by a plateau. For indium in porous glass, the origins of two-step transitions in R(T) and R(H) might be the same. At H-c(u) (or T-1) the individual grains of indium in porous glass become superconductors and at H-c(l) (or T-2) all grains are coupled. For gallium in porous glass, two superconducting transitions of R(T) at T-1=7.0 and T-2=6.3 K are observed. Between 6.35 and 6.30 K, R(T) increases sharply with decreasing temperature. The: quasiparticle tunneling or the conductor-superconductor-conductor coupling might cause the sharp rise in resistance between 6.35 and 6.30 K. At 6 K, there are two transitions at H-c(u)=2.1 T and H-c(l)=1.1 T in the R(H) for gallium in porous glass. The two different transitions of K(H) might be caused by a filamentary internal structure of gallium crystallites. There is no diamagnetism at T-1. The magnetic transition temperature T-M at 3, 4, 5, 6, and 7 T are measured; for all the cases, T-M