Further Investigations On Topological Defects

Our investigations are mainly on:φ6 domain wall, monopoles, holographic superconductor, cosmic string loops. That theφ6 domain wall, false vacuum monopole and holographic superconductor can not exist in de Sitter space was found. But global monopole can lives if it arise the condition:C1+C2≥4,D1+D2≥4. We also investigate the evolution of cosmic string loops with periodically time-dependent tension in various background, including Minkowski space, Robertson-Walker space(matter dominant and radiation dominant era) and de Sitter space. Contrary to the ones with constant tension, witch probably would collapse to form black hole, these loops will evolve oscillatorily.