Stable and Metastable vortex states and the first order transition across the peak effect region in weakly pinned 2H-NbSe_2

Abstract

The peak effect in weakly pinned superconductors is accompanied by metastable vortex states. Each metastable vortex configuration is characterized by a different critical current density J_c, which mainly depends on the past thermomagnetic history of the superconductor. A recent model [G. Ravikumar, et al, Phys. Rev. B 61, R6479 (2000)] proposed to explain the history dependent J_c postulates a stable state of vortex lattice with a critical current density J_c^{st}, determined uniquely by the field and temperature. In this paper, we present evidence for the existence of the stable state of the vortex lattice in the peak effect region of 2H-NbSe_2. It is shown that this stable state can be reached from any metastable vortex state by cycling the applied field by a small amplitude. The minor magnetization loops obtained by repeated field cycling allow us to determine the pinning and "equilibrium" properties of the stable state of the vortex lattice at a given field and temperature unambiguously. The data imply the occurence of a first order phase transition from an ordered phase to a disordered vortex phase across the peak effect.

20 pages, 10 figures. Corresponding author: S. Ramakrishnan

References in corpus (8)

• Elastic theory of flux lattices in presence of weak disorder
• Elastic Theory of pinned flux lattices
• Phase diagrams of flux lattices with disorder
• Dynamic instabilities and memory effects in vortex matter
• Metastability and Glassy Behavior of a Driven Flux-Line Lattice
• Anomalous Peak Effect in CeRu2 and NbSe2 : Fracturing of a Flux Line Lattice?
• A study of supercooling of the disordered vortex phase via minor hysteresis loops in 2H-NbSe_2
• AC Dynamics and Metastability of a Flux-Line Lattice

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• Exploring metastability via the third harmonic measurements in single crystals of $2H$-$NbS{e}_2$ showing anomalous Peak effect
• Disorder-induced two-step melting of vortex matter in Co-intercalated NbSe${}_2$ single crystals
• Interesting thermomagnetic history effects in the antiferromagnetic state of SmMn_2Ge_2
• First-order disorder-driven transition and inverse melting of the vortex lattice
• Measurement of Magnetic Relaxation in the peak regime of V3Si
• Dynamics of metastable vortex states in weakly pinned superconductors: A phenomenological model
• Peak Effect in Superconductors: Absence of Phase Transition and Possibility of Jamming in Vortex Matter
• Comparison of History Effects in Magnetization in Weakly pinned Crystals of high-$T_c$ and low-T${}_c$ Superconductors
• Thermo-magnetic history effects in the vortex state of YNi_2B_2C superconductor