Manifestation of history-dependent critical currents via dc and ac magnetization measurements in single crystals ofCeRu2and2H−

G. Ravikumar

¹

,

V. C. Sahni

²

,

Prerna Mishra

³

et al.

Abstract

A study of path dependent effects in single crystals of CeRu2 and 2H − N bSe2 show that critical current density Jc of the vortex state depends on its thermomagnetic history over a very large part of (H, T ) parameter space. The path dependence in Jc is absent above the peak position (i.e., H > Hp) of the peak effect region, which we believe identifies the complete loss of order in the vortex structure. The highly disordered FC state can be healed into a relatively ordered vortex lattice by subjecting it to a large enough change in dc field (few tens of Oe) or by shaking the FC state with sufficient ac field (few Oe).

Critical current density and magnetic phase diagrams of BaFe1.29Ru0.71As2single crystals

“…Using similar measurements close to the peak effect in CeRu 2 and NbSe 2 , [23,36] it was shown that the peak effect arose as a consequence of a first order phase transition [28]. taking cue from these studies, here too we investigate, if the SMP can arise …”

Metastability and transient effects in vortex matter near a decoupling transition

“…The existence of transient states suggests that the disordered phase can be supercooled into the ordered region [21], producing an increasing voltage response, whereas the ordered phase may be superheated into the disordered region, giving a decaying response. In addition to transient effects, pronounced memory effects and hysteretic V(I) curves have been observed near the peak effect in low temperature materials [2,[4][5][6][7][16][17][18][19][20]. Memory effects are also seen in simulations [22].…”

“…The competition between the flux-line interactions, which order the vortex lattice, and the defects in the sample, which disorder the vortex lattice, produce a remarkable variety of collective behavior [1]. One prominent example is the peak effect in low temperature superconductors, which appears near H c2 when a transition from an ordered to a strongly pinned disordered state occurs in the vortex lattice [2][3][4][5][6][7][8]. In high temperature superconductors, particularly BSCCO samples, a striking "second peak" phenomenon is observed in which a dramatic increase in the critical current occurs for increasing fields.…”

Critical depinning force and vortex lattice order in disordered superconductors

“…Vortices in type II superconductors, which can be pinned by random defect sites in the material, are a particularly ideal example of such a system since the substrate and lattice interactions can be readily tuned experimentally. In this case, a rich variety of static [1][2][3][4][5][6] and dynamical phases [2,7,8] can occur due to the competition between the repulsive vortex-vortex interactions, which tend to order the vortex lattice, and the attractive vortex-pin interactions, which tend to disorder the vortex lattice. Unlike the early studies of collective pinning of a defect-free elastic lattice, recent experimental and theoretical work point to the importance of topological defects in pinned vortex matter.…”