Synthesis and Characterization of Mo–Nb Films Superconducting at 100–200 mK.

Authors :: Yefremenko, V.
Zhang, J.
Lisovenko, M.
Barry, P.
Bender, A.
Cecil, T.
Chang, C.
Divan, R.
Kuhlmann, S.
Lowitz, A.
Novosad, V.
Padin, S.
Pearson, J.
Wang, G.
Source :: Journal of Low Temperature Physics; Apr2020, Vol. 199 Issue 1/2, p306-311, 6p
Publication Year :: 2020
Abstract: We have developed a new transition-edge sensor material with critical temperature (T<subscript>c</subscript>) in the range 100–200 mK. The new material is a solid solution of two superconducting components, Mo<subscript>x</subscript>Nb<subscript>1−x</subscript>, co-sputtered from two high-purity single-component targets (Mo and Nb). The T<subscript>c</subscript> has a minimum (dT<subscript>c</subscript>/dx = 0) at an intermediate concentration of the components. We have optimized the deposition parameters and composition to provide films with a sharp superconducting transition at ~ 150 mK. We investigated structural features of the films and surface morphology using X-ray diffraction (XRD) and scanning electron microscopy. The XRD measurements indicate that the grown films are polycrystalline, with a preferred orientation along the (110) crystal direction and a clear correlation between superconducting properties and film microstructure. [ABSTRACT FROM AUTHOR]