圆对称环域Josephson结中的零场台阶

ZERO FIELD STEPS IN AN ANNULAR SYMMETRIC JOSEPHSON JUNCTION

对计及干涉项的描述圆对称环域Josephson结扰动sine-Gordon方程数值研究表明:在无外磁场时,对于内外半径分别为7.5λ_1和12.5λ_1的结,在它的Ⅰ-V特性曲线上呈现两支零场台阶,它们分别对应于单孤子和三孤子激发,双孤子的激发是不稳定的,它仅存在于暂态过程之中,三孤子激发相当于一维结中三孤子的对称模式,且伴随着包括不同振荡周期等的运动不规则性。

A numerical study of a perturbed sine-Gordon equation (SGE) in an annularly symmetric Josephson junction by considering the cosΦ-term is carried out in this paper. The numerical results show that in the absence of external applied field there are two branches of the zero field steps (ZFS) in the I-V characteristic; the lower voltage ZFS corresponds to the single soliton excitation (1-ZFS) and the higher voltage one corresponds to three solitons exicitation (3-ZFS). In our calculations for the definite size and parameters of the annularly symmetric Josephson junction, the two solitons excitation is unstable. The three solitons excitation is similar to the 3-ZFS with the symmetric mode in the one-dimensional overlap Josephson junction except that there exist amplitude molulation for the time behaviour in both of the voltages <φτ>000 and φTTT(ρ1,τ).