Correlation between structural transformation and superconductivity in B2 alloys V-Ru-Os

The inter-relationship between structural transformation and superconductivity has been studied on B2 systems Vsub(54-x)Ru46Ossub(x), V54Rusub(46-x)Ossub(x) and V52Rusub(48-x)Ossub(x) with 0<=x<=4. An increase of the parameter x in Vsub(54-x)Ru46Ossub(x), where the electron-atom ratio e/a increases linearly with x, raises the transformation temperature Tsub(L) sharply while lowering the superconducting transition temperature Tsub(c) rapidly. This is in contrast with the results for both systems V54Rusub(46-x)Ossub(x) and V52Rusub(48-x)Ossub(x), where e/a is a constant independent of x. All samples in V54Rusub(46-x)Ossub(x) with e/a=6.38 undergo no structural transformation, while showing superconductivity at nearly the same temperatures around 5 K. All samples in V52Rusub(48-x)Ossub(x) with e/a=6.44, however, show no superconductivity, while undergoing transformation at nearly the same temperatures around 200 K. Taken together, these facts confirm that both Tsub(L) and Tsub(c) are completely dominated by the value of e/a; the lowering of Tsub(L), which is accompanied by a decrease of e/a, causes sharp enhancement of Tsub(c). This provides decisive evidence for the electronic transition and its strong correlation with superconductivity. (author)