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The temperature of shock compressed iron has been measured to 340 GPa, using well characterized iron films sputtered on transparent diamond substrates and a 1 ns time-resolved optical method. We find a knee on the (P,T) iron Hugoniot indicating melting at 6350 K and 235 GPa and at 6720 K and 300 GPa. An extrapolation yields an iron melting temperature of 6830 (\ifmmode\pm\else\textpm\fi{} 500) K at 330 GPa, the pressure of the Earth inner-outer core boundary. Implication of the melting data for the iron phase diagram is also discussed.

We report results of the study of electron tunneling into thin films of the new high-${T}_{c}$ superconductor La-Sr-Cu-O. Both sandwich-type tunneling with a Pb counterelectrode and point-contact tunneling have been successfully achieved. The results show exceptionally large energy gaps in these materials (roughly 20, 30, and possibly even 60 mV), larger than previously obtained on bulk sintered powders. We interpret these results as due to large anisotropy in this material or due to the presence of a a very high-${T}_{c}$ layer near the surface of the films. The method of preparation of this new superconductor in thin film form is also discussed.

The new high-${T}_{c}$ superconductor YBaCuO was prepared and characterized. Measurements were performed to determine the superconducting and magnetic properties of the samples. Onset of superconductivity was found above 90 K. Antiferromagnetism was also observed, probably associated with the nonsuperconducting pairs of the samples. Modest critical current density as well as large upper critical fields were inferred from the data.

We report results of a study of electron tunneling into bulk samples of the new high-${T}_{c}$ superconductor Y-Ba-Cu-O using point-contact tunneling. Based on a superconductive tunneling interpretation, the results show exceptionally large energy gaps in these materials (roughly 2\ensuremath{\Delta}=100 meV), implying 2\ensuremath{\Delta}/${k}_{C}$${T}_{c}$\ensuremath{\sim}13. Similar values were found previously by us for La-Sr-Cu-O. We also see Structure in the I-V curves similar to that seen in La-Sr-Cu-O. On the basis of the asymmetries observed in the I-V characteristics, we believe that the natural tunneling barrier on this material is of the Schottky type.