Effects of disorder and dimensionality on the vortex phase diagram at low temperature in amorphous films
Abstract
We present measurements of dc and ac complex resistivities for amorphous Mo xSi 1- x films with different disorder and dimensionality (film thickness t). For thicker films with t=100 and 30 nm we determine the vortex-glass-transition (VGT) line Bg( T) which persists down to low enough temperatures T up to high fields B near Bc2(0), where Bc2(0) is an upper critical field at T=0. The finite quantum-vortex-liquid (QVL) phase at T=0, Bg(0)< B< Bc2(0), is observed for these films. We find a trend for the QVL phase to increase as the film becomes more resistive and/or thinner. This result is consistent with a view that the QVL phase is driven by strong quantum fluctuations, which are enhanced with increasing disorder and with decreasing dimensionality. For the thinnest film with t=6 nm, both the dc resistivity and vortex relaxation time follow the activated T dependence, suggestive of two-dimensional VGT.
- Publication:
-
Physica C Superconductivity
- Pub Date:
- October 2003
- DOI:
- 10.1016/S0921-4534(03)01045-1
- Bibcode:
- 2003PhyC..392..410O