Collective flux pinning in hexatic vortex fluid in a-MoGe thin film

Abstract

We investigate the magnetic field variation of the thermally activated flux flow resistivity, ρ TAFF and flux flow critical current density, J c , in a weakly pinned thin film of the amorphous superconductor aMoGe, where vortices are in a fluid state over a large range of magnetic fields. We show that both quantities can be understood within the framework of collective pinning theory. In particular, our results demonstrate that a 'peak effect' can arise at the order-disorder transition of the vortex lattice even when both the ordered and disordered states are vortex fluids, such as the boundary between a hexatic vortex fluid and an isotropic vortex liquid.

Transport signatures of fragile-glass dynamics in the melting of the two-dimensional vortex lattice

“…much larger than the sample thickness. Therefore, the vortex lattice (VL) in these films is indeed 2D, although the SC state is 3D (thickness > ξ, where ξ ∼ 5 nm is the SC coherence length [18]).…”

“…a-MoGe films with thickness t = 22 nm were grown on surface-oxidized Si substrate through pulsed laser deposition. The reported chemical stoichiometry of these thin films, as seen from the dispersive X-ray analysis, is Mo 71±1.5 Ge 29±1.5 ; their properties have been described in detail elsewhere [8,9,18]. The films were capped with a 2 nm thick Si layer to prevent surface oxidation, and patterned in Hall bar geometry using a shadow mask.…”

“…ρ) becomes zero, that is, falls below the experimental noise floor (see also Methods). The characteristic length scales for vortex distortions parallel to the applied H and caused by thermal fluctuations or pinning are of the order of several µm [18,19], i.e. much larger than the sample thickness.…”

Noncentrosymmetric superconductivity and peak effect in rhenium based materials

“…palavras-chave: supercondutividade não-centrossimétrica; efeito de pico; rede de vortex; rênio and (b) are the measurements of the magnetic field dependence of the critical current and electrical resistivity, respectively [122]. (c) Magnetization data of the borocarbide superconductor YNi 2 B 2 C exhibiting a characteristic peak near H c2 [123].…”

“…Then, shown in Figure2.8 is a collection of experimental results in various systems exhibiting the peak effect. The critical current density J c of a MoGe thin film[122] in Figure2.8(a) declines monotonically before starting to increase at the peak effect region (highlighted in yellow). Field dependent electrical resistivity of the same sample is also shown in Figure2.8(b), having a resistance minimum just…”