Enhancement of the quantum-liquid phase by increased resistivity in thick a-MoxSi1-x films -: art. no. 067001

Effects of normal-state resistivity rho(n) on the vortex phase diagram at low temperature T have been studied based on dc and ac complex resistivities for thick amorphous MoxSi1-x films. It is commonly observed irrespective of rho(n) that, in the limit T=0, the vortex-glass-transition line B-g(T) is independent of T and extrapolates to a field below the T=0 upper critical field B-c2(0), indicative of the quantum-vortex-liquid (QVL) phase in the regime B-g(0)<B<B-c2(0). The relative width of the QVL phase increases along the B and T axes approximately proportional to rho(n). This result is consistent with a view that the QVL phase is caused by strong quantum fluctuations, which are enhanced with increasing rho(n).