Phys. Rev. B 71, 214520 (2005) [14 pages]Spin and spin-wave dynamics in Josephson junctionsReceived 15 December 2004; revised 17 February 2005; published 22 June 2005 We extend the Keldysh formulation to quantum spin systems and derive exact equations of motion. This allows us to explore the dynamics of single spins and of ferromagnets when these are inserted between superconducting leads. Several new effects are reported. Chief amongst these are nutations of single S=1∕2 spins in Josephson junctions. These nutations are triggered by the superconducting pairing correlations in the leads. Similarly, we find that on rather universal grounds, magnets display unconventional spin wave dynamics when placed in Josephson junctions. These lead to modifications in the tunneling current. © 2005 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.71.214520
DOI:
10.1103/PhysRevB.71.214520
PACS:
74.50.+r, 75.20.Hr, 73.40.Gk
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