Numerical analysis of the magnetic-field-tuned superconductor-insulator transition in two dimensions

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Abstract

Ground state of the two-dimensional hard-core-boson model subjected to external magnetic field and quenched random chemical potential is studied numerically. In experiments, magnetic-field-tuned superconductor-insulator transition has already come under through investigation, whereas in computer simulation, only randomness-driven localization (with zero magnetic field) has been studied so far: The external magnetic field brings about a difficulty that the hopping amplitude becomes complex number (through the gauge twist), for which the quantum Monte-Carlo simulation fails. Here, we employ the exact diagonalization method, with which we demonstrate that the model does exhibit field-tuned localization transition at a certain critical magnetic field. At the critical point, we found that the DC conductivity is not universal, but is substantially larger than that of the randomness-driven localization transition at zero magnetic field. Our result supports recent experiment by Marković et al. reporting an increase of the critical conductivity with magnetic field strengthened.

Original languageEnglish
Pages (from-to)147-155
Number of pages9
JournalPhysica C: Superconductivity and its Applications
Volume353
Issue number1-2
DOIs
Publication statusPublished - May 1 2001

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Electron transitions
Superconducting materials
numerical analysis
Numerical analysis
insulators
Magnetic fields
magnetic fields
complex numbers
conductivity
Bosons
Chemical potential
Ground state
Gages
critical point
bosons
computerized simulation
direct current
Experiments
ground state
Computer simulation

Keywords

  • Critical conductivity
  • Dynamical critical exponent
  • Exact-diagonalization method
  • Finite-size-scaling method
  • Randomness
  • Superconductor-insulator transition

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

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title = "Numerical analysis of the magnetic-field-tuned superconductor-insulator transition in two dimensions",
abstract = "Ground state of the two-dimensional hard-core-boson model subjected to external magnetic field and quenched random chemical potential is studied numerically. In experiments, magnetic-field-tuned superconductor-insulator transition has already come under through investigation, whereas in computer simulation, only randomness-driven localization (with zero magnetic field) has been studied so far: The external magnetic field brings about a difficulty that the hopping amplitude becomes complex number (through the gauge twist), for which the quantum Monte-Carlo simulation fails. Here, we employ the exact diagonalization method, with which we demonstrate that the model does exhibit field-tuned localization transition at a certain critical magnetic field. At the critical point, we found that the DC conductivity is not universal, but is substantially larger than that of the randomness-driven localization transition at zero magnetic field. Our result supports recent experiment by Marković et al. reporting an increase of the critical conductivity with magnetic field strengthened.",
keywords = "Critical conductivity, Dynamical critical exponent, Exact-diagonalization method, Finite-size-scaling method, Randomness, Superconductor-insulator transition",
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N2 - Ground state of the two-dimensional hard-core-boson model subjected to external magnetic field and quenched random chemical potential is studied numerically. In experiments, magnetic-field-tuned superconductor-insulator transition has already come under through investigation, whereas in computer simulation, only randomness-driven localization (with zero magnetic field) has been studied so far: The external magnetic field brings about a difficulty that the hopping amplitude becomes complex number (through the gauge twist), for which the quantum Monte-Carlo simulation fails. Here, we employ the exact diagonalization method, with which we demonstrate that the model does exhibit field-tuned localization transition at a certain critical magnetic field. At the critical point, we found that the DC conductivity is not universal, but is substantially larger than that of the randomness-driven localization transition at zero magnetic field. Our result supports recent experiment by Marković et al. reporting an increase of the critical conductivity with magnetic field strengthened.

AB - Ground state of the two-dimensional hard-core-boson model subjected to external magnetic field and quenched random chemical potential is studied numerically. In experiments, magnetic-field-tuned superconductor-insulator transition has already come under through investigation, whereas in computer simulation, only randomness-driven localization (with zero magnetic field) has been studied so far: The external magnetic field brings about a difficulty that the hopping amplitude becomes complex number (through the gauge twist), for which the quantum Monte-Carlo simulation fails. Here, we employ the exact diagonalization method, with which we demonstrate that the model does exhibit field-tuned localization transition at a certain critical magnetic field. At the critical point, we found that the DC conductivity is not universal, but is substantially larger than that of the randomness-driven localization transition at zero magnetic field. Our result supports recent experiment by Marković et al. reporting an increase of the critical conductivity with magnetic field strengthened.

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