Crossovers in the thermal decay of metastable states in discrete systems

Article

关键词: HIGH-TEMPERATURE SUPERCONDUCTORS;    LONG JOSEPHSON-JUNCTIONS;    DC SQUID;    LAYERED SUPERCONDUCTORS;    QUANTUM;    ACTIVATION;    VORTICES;    NUCLEATION;   

DOI  :  10.1103/PhysRevB.60.9763

来源: SCIE

【 摘 要 】

The thermal decay of linear chains from a metastable state is investigated. A crossover from rigid to elastic decay occurs when the number of particles, the single-particle energy barrier, or the coupling strength between the particles is varied. In the rigid regime, the single-particle energy barrier is small compared to the coupling strength, and the decay occurs via a uniform saddle-point solution, with all degrees of freedom decaying instantly. Increasing the barrier one enters the elastic regime, where the decay is due to bent saddle-point configurations using the elasticity of the chain to lower their activation energy. Close to the rigid-to-elastic crossover, nucleation occurs at the boundaries of the system. However, in large systems, a second crossover from boundary to bulk nucleation can be found within the elastic regime, when the single-particle energy barrier is further increased. We compute the decay rate in the rigid and elastic regimes within the Gaussian approximation. Around the rigid-to-elastic crossover, the calculations are performed beyond the steepest-descent approximation. In this region, the prefactor exhibits a scaling property. The theoretical results are discussed in the context of discrete Josephson transmission lines and pancake vortex stacks that are pinned by columnar defects.

【 授权许可】

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