Superconducting UBe13 thin films

Of the known heavy fermion superconductors only UBe13 can have a low resistivity ratio and still go superconducting. In addition, it is a line compound with a melting temperature of nearly twice that of the constituents. These facts make UBe13 a promising choice for fabrication in thin film form. We have successfully made 2000 A UBe13 films by coevaporation of uranium and beryllium on 7000C substrates which were then heated in situ to 11000C. These films were polycrystalline as shown by X-ray diffraction and have Tsub(c)'s of 0.85 K, that of the bulk. The resistivity rise at approximately 2 K and the strong negative magnetoresistance were also of the same magnitude as that of the bulk, as were both the perpendicular and parallel critical fields. Thin film of UBe13 will make more accessible tunneling and proximity effect experiments which can help elucidate the nature of the superconductivity of this compound. (orig.)