Monte Carlo study of vortex fluctuations in vortex-line phases

Journal Article · Wed May 01 04:00:00 EDT 1996 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.53.11837· OSTI ID:283891

Carneiro, G ^[1]

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1. Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21945-970 Rio de Janeiro-RJ (Brazil)

The effects of vortex fluctuations on the phase diagram of clean, isotropic, type-II superconductors placed in an external magnetic field {ital H} are investigated by Monte Carlo (MC) simulations of a lattice London model. These simulations are carried out at constant {ital H} and allow for a finite penetration length {lambda}. New results supporting previously reported [G. Carneiro, Phys. Rev. Lett. {bold 75}, 521 (1995)] evidence for melting of the vortex-line lattice into an entangled vortex liquid, in the region {lambda}{approx_gt}{ital a}{sub {ital v}} ({ital a}{sub {ital v}}= mean intervortex spacing), is presented. Fluctuations involving thermal excitation of vortex loops are also investigated. It is found that these fluctuations can be neglected in a temperature region extending from zero to well into the entangled vortex- liquid phase. In this temperature region, the correlations between the field-induced vortices in the entangled vortex liquid are found to be in good qualitative agreement with theoretical predictions based on the analogy between vortex lines and two-dimensional bosons. By comparing MC simulation results with and without an external magnetic field, evidence is found that the entangled vortex liquid evolves smoothly into the normal state as the temperature increases. {copyright} {ital 1996 The American Physical Society.}

• OSTI ID: 283891
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 17 Vol. 53; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
FLUCTUATIONS
LONDON EQUATION
MAGNETIC FIELDS
MAGNETIC FLUX
MONTE CARLO METHOD
PENETRATION DEPTH
TEMPERATURE DEPENDENCE
TYPE-II SUPERCONDUCTORS