Effect of thermal fluctuations on Josephson vortex dynamics in intrinsic Josephson junctions

Abstract

We have made a numerical study of the effect of thermal fluctuations on Josephson vortex dynamics in a stack of intrinsic Josephson junctions. Our simulations successfully reproduced the experimental results such as the field dependence of the critical current, the noise-rounded current–voltage characteristics and a periodic oscillation of the Josephson vortex flow resistance. It was confirmed that the oscillation period of the Josephson vortex flow resistance is related to the modulation of the critical current rather than the vortex lattice structure. We found that in the dynamic state the triangular vortex lattice becomes stable independent of the field even at zero temperature. Furthermore, at finite temperature, a thermally activated disordered vortex flow is observed in a low-bias region where the Lorentz force is not large enough to induce the collective flow of vortices.

Magnetic oscillations of critical current in intrinsic Josephson-junction stacks

“…Such behavior of the critical current has been recently reproduced by numerical simulations by Irie and Oya. 21 Experimentally, the crossover between Φ 0 /2-and Φ 0 -periodic oscillations has been observed in the fluxflow voltage by Kakeya et al 15 The crossover field can be arbitrarily defined as a field at which a kΦ 0 -peak in the product ΦJ c drops below the half of a (k + 1/2)Φ 0peak. At larger L the crossover takes place at larger field and larger Φ/Φ 0 but it always occurs at the same ratio h/L, h/L ∼ 1.6.…”

“…15,16,17 The crossover in the voltage oscillations also has been studied numerically. 16,21 In the region L ∼ L B the lattice structure is determined by competition between two energies: the interaction with boundaries and the bulk shearing interaction between the Josephson-vortex planar arrays in neighboring layers. The interaction with the boundaries favors the aligned rectangular arrangement of the Josephson vortices while the local shearing interaction favors the triangular lattice.…”

Josephson vortex lattice in layered superconductors

“…70. Lattice structures also have been extensively explored numerically 46,48,71,72 and both approaches give identical results. In a small-size sample the lattice structure is determined by two competing interactions: the interaction with boundaries that favors an aligned rectangular configuration and the bulk shearing interaction between neighboring layers which favors a triangular configuration.…”

Shapiro steps in Bi2Sr2CaCu2O8+δ intrinsic Josephson junctions in magnetic field

“…[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] It is sure that a pioneering work done by Sakai et al 20 is the starting point to understand the fluxon dynamics in BSCCO IJJs with a stacking structure. The is the phase difference of a SIS Josephson junction as a function of spatial variable x and real time t. It is also known that Eq.…”