Thermal and electromagnetic properties of Bi₂ Sr₂ CaCu₂O₈ intrinsic Josephson junction stacks studied via one-dimensional coupled sine-Gordon equations

We used one-dimensional coupled sine-Gordon equations combined with heat diffusion equations to numerically investigate the thermal and electromagnetic properties of a 300 μm long intrinsic Josephson junction stack consisting of N=700 junctions. The junctions in the stack are combined with M segments where we assume that inside a segment all junctions behave identically. Most simulations are for M=20. For not too high bath temperatures there is the appearance of a hot spot at high-bias currents. In terms of electromagnetic properties, robust standing-wave patterns appear in the current density and electric field distributions. These patterns come together with vortex/antivortex lines across the stack that correspond to π-kink states, discussed before in the literature for a homogeneous temperature distribution in the stack. We also discuss scaling of the thermal and electromagnetic properties with M, on the basis of simulations with M between 10 and 350.