Eur. Phys. J. B (2016) 89: 68
https://doi.org/10.1140/epjb/e2016-60478-y

Regular Article

Superconductor-insulator transition of Josephson-junction arrays on a honeycomb lattice in a magnetic field

Laboratório Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, 12227-010 São José dos Campos, SP, Brazil

^a e-mail: enzo@las.inpe.br

Received: 15 June 2015
Received in final form: 24 October 2015
Published online: 14 March 2016

Abstract

We study the superconductor to insulator transition at zero temperature in a Josephson-junction array model on a honeycomb lattice with f flux quantum per plaquette. The path integral representation of the model corresponds to a (2 + 1)-dimensional classical model, which is used to investigate the critical behavior by extensive Monte Carlo simulations on large system sizes. In contrast to the model on a square lattice, the transition is found to be first order for f = 1 / 3 and continuous for f = 1 / 2 but in a different universality class. The correlation-length critical exponent is estimated from finite-size scaling of vortex correlations. The estimated universal conductivity at the transition is approximately four times its value for f = 0. The results are compared with experimental observations on ultrathin superconducting films with a triangular lattice of nanoholes in a transverse magnetic field.