Nature of vortex lattice disordering at the onset of the peak effect

Abstract

We report a transport study of the onset of the peak effect in a 2H-NbSe 2 single crystal with very weak pinning. At low driving current, we find that at the onset of the peak effect, where the resistance starts to dip with increasing field, the resistance is hysteretic upon field cycling. The resistance is higher for upward field sweeps than for downward sweeps. The difference between the two has a double-peak feature, indicative of two-stage disordering of a vortex lattice. The resistance hysteresis and the two-stage feature disappear after cold-working the sample. The onset field of the peak effect is found to depend on driving current nonmonotonically, suggesting reentrant driven disorder-order and order-disorder transitions in the peak-effect regime.

Possible reordering of vortex matter near the end point of the second peak line in theYBa2Cu3OΣταμόπουλος1, Pissas2, Bondarenko3 2002Phys. Rev. B273220View full textAdd to dashboardCite

“…In the past years a lot of work is done in the subject of dynamic transitions of vortex matter when subjected to an applied driving force. [37][38][39][40][41][42][43][44][45][46] Theoretical treatment argues that a static disordered vortex solid could be, dynamically, transformed to a moving solid state ͑that possibly retains crystalline order in some degree͒ under the influence of high driving forces. [38][39][40][41][42] We believe that such a plysical process could be related to the results presented here.…”

From the second magnetization peak to peak effect. A study of superconducting properties in Nb films and MgB2bulk samples

“…On the other hand, in disordered samples, it is the static disorder that transforms the vortex lattice into an amorphous vortex solid. This behavior has been observed in the high-T c compounds HgBa 2 CuO 4+δ [18] and YBa 2 Cu 3 O 7−δ [19] and in the low-T c superconductors 2H-NbSe 2 [58,59], CeRu 2 [59] and X 3 Rh 4 Sn 13 [4,57] (X=Ca,Yb). In our case, we observed a sharp drop (∆T ≈ 100 mK) at the end points of the PE which is also hysteretic.…”

“…First, a local peak at T onset , and second a dip at T peak . This is the well-known PE in the critical current J c (the minimum in the measured voltage corresponds to a maximum/peak in the critical current J c ), which was observed in high-T c compounds [4,17,18,51], in superconductors of intermediate-T c as pristine and Carbon-doped MgB 2 [42,52,53], in Nb [9,10,54,55,56] and other low-T c [4,57,58,59] disordered superconductors. The comparison to our magnetic measurements (not shown here) revealed that the PE almost coincides with the upper-critical fields (see fig.…”

STM Imaging of Flux Line Arrangements in the Peak Effect Regime

“…The discovery of the high temperature superconductors made it relevant to also consider thermal fluctuations as a third energy scale, which lead to melting by suppression of c 66 . This would then yield a peak effect as a precursor of the melting transition [4,5,6].Experimentally, it is hard to probe which mechanism is predominant, because one needs information about structural changes of the vortex lattice positional order as a function of time. Small angle neutron scattering (SANS) yields structural information along the field direction averaged over the sample volume, i.e., about the amount of entanglement of the VL.…”