Persistent spin currents induced by a spatiallydependent magnetic field in a spin1/2 Heisenberg antiferromagnetic ring
Abstract
We show that a spatiallydependent magnetic field can induce a persistent spin current in a spin1/2 Heisenberg antiferromagnetic ring, proportional to the solid angle subtended by the magnetic field on a unit sphere. The result is a direct consequence of Berry "parallel transport" in space. The magnitude of the spin current is determined by the ratio of longitudinal and transverse exchange interactions $J_\parallel/J_\perp$ and by the magnetic field. For large magnetic fields the Zeeman energy strongly renormalizes the Ising term giving rise to a maximum spin current. In the limit of $J_\parallel/J_\perp\ll1$ the amplitude of the current behaves like $1(J_\parallel/J_\perp)^2$. In the opposite limit $\pi J_\perp> J_\parallel>J_\perp$ the amplitude scales as $\sqrt{J_\parallel/ J_\perp}\exp{(\sqrt{J_\parallel/J_\perp})}$.
 Publication:

arXiv eprints
 Pub Date:
 May 2004
 arXiv:
 arXiv:condmat/0405659
 Bibcode:
 2004cond.mat..5659S
 Keywords:

 Condensed Matter  Mesoscopic Systems and Quantum Hall Effect;
 Condensed Matter  Materials Science
 EPrint:
 14 pages plus one figure