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

Yoshihiro Nishiyama
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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 Markovi'c et al. reporting an increase of the critical conductivity with magnetic field strengthened.

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Yoshihiro Nishiyama. 2000-11-01. Numerical analysis of the magnetic-field-tuned superconductor-insulator transition in two dimensions. https://doi.org/10.1016/s0921-4534(00)01741-x

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