This article is cited in 1 paper

Indirect interaction between nuclear spins in easy-axis antiferromagnets

A. A. Kokin^a, V. A. Kokin<sup>b

a</sup> Institute of Physics and Technology, RAS, Moscow, Russia
^b Kotel'nikov Institute of Radio Engineering and Electronics, RAS, Moscow, Russia

Abstract: We consider two atoms with nuclear spins $I=1/2$ belonging to a regular chain (spin register) of isotopes substituting basic nuclear-spin-free atoms in a plate of an antiferromagnet with the easy anisotropy axis. A constant external magnetic field is assumed to be directed along the easy axis perpendicular to the plate plane and to have a constant gradient along the register direction. For a simple model, we diagonalize the spin Hamiltonian in a spin-wave approximation using the Bogoliubov–Tyablikov transformation. We show that in the presence of a nonuniformity of the external magnetic field, the indirect interaction between nuclear spins caused by the hyperfine interaction of nuclear spins with virtual spin waves in the antiferromagnet can increase and even oscillate depending on the distance between the considered spins if the local field at the midpoint between them is close to the field of the orientational phase transition to the spin-flop phase in a homogeneous antiferromagnet.

Keywords: antiferromagnet with easy anisotropy axis in nonuniform external field, Bogoliubov–Tyablikov transformation, orientational phase transition to the spin-flop phase, indirect interaction of nuclear spins.

Received: 27.02.2011
Revised: 27.03.2011

DOI: 10.4213/tmf6694

 English version: Theoretical and Mathematical Physics, 2011, 168:3, 1258–1270

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