1958/07/01 by J. F. Cochran, D. E. Mapother · 2 citations
Materials Science · Physics and Astronomy · #Aluminium #Condensed matter physics #Crystallite #Energy (signal processing) #Magnetic Properties and Applications #Materials science #Physics #Quantum mechanics #Relaxation (psychology) #Superconductivity #Superconductivity in MgB2 and Alloys #Surface and Thin Film Phenomena #Transition temperature
paper · doi:10.1103/physrev.111.132
openalex publication_date 1958/07/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/11
Further results on the superconducting properties of aluminum are given which supplement those previously reported. The critical field curve for pure Al has been measured by using a paramagnetic salt as a thermometer. Except for a region very near Tc, our data are accurately represented by the parabolic relation, Hc=H0[1\ensuremath-(\fracTTc)2], where Tc=1.196\ifmmode±\else\textpm\fi0.005\ifmmode^∘\else\textdegree\fiK and Hc is about 99\ifmmode±\else\textpm\fi1 gauss. The excellent reproducibility of the S\ensuremath-N transition in Al suggests that it may serve as a useful secondary thermometric standard near 1\ifmmode^∘\else\textdegree\fiK. Further observations are reported on the broadening tendency of magnetically measured transitions in single-crystal specimens near Tc. It is also found that polycrystalline specimens of the same material do not show the broadening effect. A semiquantitative theory of the intermediate state is applied to explain the observation that the magnetic transition is sharper than predicted on the basis of specimen geometry at temperatures well below Tc. The difference in sharpness can be explained as a contribution of the interphase free energy whose order of magnitude has been estimated with fair success from the observed shape of the magnetic transition.