Ground state of a superconducting π ring array under external magnetic fields

• 来源期刊: 中国物理（英文版）
• 关键词: π ring array Josephson junction spontaneous magnetization
• 年，卷（期）: 2007,（5）
• 页码范围: 1450-1458
• 页数: 9页
• 语种: 英文

摘要

The ground state of a two-dimensional square superconducting TT ring array has been investigated. The circulating currents of the π ring array will spontaneously magnetize to the 'antiferromagnetic' arrangement with directions of the nearest-neighbouring currents circulating oppositely in the absence of an external magnetic field. It is found that the external magnetic field could destroy the anti-parallel configuration effectively. The external magnetic field needed to destroy the anti-parallel configuration is related to the superconducting π ring's inductance parameter β= 2πLIc/φ0.For a small β the anti-parallel configuration, which is the lowest-energy ground state of the system, will be fully destroyed and changed to the configuration that the circulating currents have the same direction and parallel to the external magnetic field when the magnetic flux reachesφ0/4 in each ring. Moreover, the magnetic field needed to destroy the anti-parallel configuration will be very small when βis large enough.