Universal conductivity in the boson Hubbard model in a magnetic field

Journal Article · Fri Apr 01 04:00:00 EST 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.49.9794· OSTI ID:5118645

Cha, M ^[1]; Girvin, S M ^[2]

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1. Department of Physics and Astronomy and Center for Computational Sciences, University of Kentucky, Lexington, Kentucky 40506 (United States)
2. Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States)

The universal conductivity at the zero-temperature superconductor-insulator transition of the two-dimensional boson Hubbard model is studied for cases both with and without magnetic field by Monte Carlo simulations of the (2+1)-dimensional classical [ital XY] model with disorder represented by random bonds correlated along the imaginary time dimension. The effect of the magnetic field is characterized by the frustration [ital f]. From the scaling behavior of the stiffness, we determine the quantum dynamical exponent [ital z], the correlation length exponent [nu], and the universal conductivity [sigma][sup *]. For the disorder-free model with [ital f]=1/2, we obtain [ital z][approx]1, 1/[nu][approx]1.5, and [sigma][sup *]/[sigma][sub [ital Q]]=0.52[plus minus]0.03, where [sigma][sub [ital Q]] is the quantum conductance. We also study the case with [ital f]=1/3, in which we find [sigma][sup *]/[sigma][sub [ital Q]]=0.83[plus minus]0.06. The value of [sigma][sup *] is consistent with a theoretical estimate based on the Gaussian model. For the model with random interactions, we find [ital z]=1.07[plus minus]0.03, [nu][approx]1, and [sigma][sup *]/[sigma][sub [ital Q]]=0.27[plus minus]0.04 for the case [ital f]=0, and [ital z]=1.14[plus minus]0.03, [nu][approx]1, and [sigma][sup *]/[sigma][sub [ital Q]]=0.49[plus minus]0.04 for the case [ital f]=1/2.

• DOE Contract Number: FG02-90ER45427
• OSTI ID: 5118645
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 49:14; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

665411* -- Basic Superconductivity Studies-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BOSONS
CALCULATION METHODS
CRYSTAL MODELS
ELASTICITY
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HUBBARD MODEL
MAGNETIC FIELDS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MONTE CARLO METHOD
PHYSICAL PROPERTIES
SCALING LAWS
SUPERCONDUCTIVITY
TENSILE PROPERTIES
TWO-DIMENSIONAL CALCULATIONS